Do you remember when Bernie Sanders gave Hillary Clinton, his only real rival for the Democratic nomination, a pass on her “damn emails” saying that the American public was sick and tired of hearing about them? Hard to believe, but that was on 13 October last year.

If she thought that with that one gift she would be rid of the controversy and could focus her campaign on the issues that she and Bernie agreed people really cared about - the economy, above all - it was later to become clear she was entirely mistaken.

But then in July, the FBI said it had concluded its investigation of why she had thought it OK to use a private server while Secretary of State during the first Obama administration. Sure, the FBI director, James Comey, was later to fault her for being “extremely careless” in her actions, but the message was clear and certain: there would no criminal charges filed in the case.

Even that, of course, didn’t quiet the furore. Donald Trump led chants of “lock her up” at his party’s convention in Cleveland later than month anyway and has since worked hard to fuel the suggestion that his rival for the White House only escaped prosecution because of a conspiracy by the Washington elite to protect their own from legal impugnment.

The theory has seemed ever more credible to Trump supporters, for whom the email affair became their last real hope of halting Ms Clinton’s seeming relentless march to the White House. (Mr Trump clearly wasn’t being much help with his repeated gaffes and embarrassments, not least the tapes revealing his past behaviour towards women and the slow parade of now more than ten women claiming they have been abused by him in the past.)

They pointed to the revelation that on 27 June, Bill Clinton met privately with Loretta Lynch, the US Attorney General, in his plane on the tarmac at Phoenix Airport at the very time when her Justice Department was due to respond to the FBI’s recommendation that no charges be laid against the Democratic candidate, his wife.

More recently, the bad smell that has always accompanied the email scandal has been wafted back into the campaign by Julian Assange and his Wikileaks worker bees. “Did you have any idea of the depth of this story?” John Podesta is caught asking someone in Ms Clinton’s inner circle when The New York Times first reported her use of the private server back in April 2015.

The man he was addressing was Robby Mook, now her chief strategist. He at the time was apparently clueless as to what the vastly more seasoned Mr Podesta was talking about. “Nope,” wrote back Mr Mook. “We brought up the existence of emails in reserach [sic] this summer but were told that everything was taken care of.”

But wind forward to Friday, when the story potentialy got a whole lot deeper than pehaps even Mr Podesta ever imagined. The FBI sent Congress a letter saying it had uncovered still more emails that may be “pertinent” to the case and was looking into them. Translation: just 11 days out from the election the FBI may be about to re-open the investigation.

Ms Clinton was aloft flying to Iowa when the news broke. The pressure in the cabin surely went up a few notches as she and her aides contemplated the storm that would greet them upon landing. Meanwhile in New Hampshire, Mr Trump appeared before supporters in gleeful mood.

A few deep breaths may be required. We cannot say if this an October bombshell or an October squib. For its part, the FBI wouldn’t detail the precise nature of these emails or why it thinks they might have relevance to Ms Clinton's private server. They do not appear to have been emails exchanged on her server or discovered in connection with the ongoing dumps by WikiLeaks. Rather - a somewhat surreal new detail - they seem to have come to the FBI's attention in the course of the quite separate investigation into the sexting activities of former Congressman Anthony Weiner. His wife, from whom he is now separated, is Huma Abedin, Ms Clinton's closest confidante.

Most important, we as yet have no clue as towhat they might - or might not - reveal. It's possible, if the FBI takes it time, that will remain the case beyond the election.

But Ms Clinton will be surely in trouble if somehow they show fresh evidence of her having received and sent emails on her home-cooked server that were clearly marked as being classified. Ever more cataclysmic would be something in the new material offering evidence that any of them were hacked by foreign powers, say Russia. That would fairly much put the dagger into any assertion by her that using the private email was a mistake, but not a serious one.

While the polls speak of a landslide, this reporter has always been sceptical. You don’t have to spend much time in the heartland to see the sheer breadth of distrust of Ms Clinton. That distrust seemed to find a new friend on Friday thanks to the FBI and Mr Comey.

But again, hold tight. The new storm could still prove to be a squall. The next installment from the FBI could be: false alarm, there is nothing there.