Gov. Cuomo had seven days of smug last week, all at Mayor de Blasio’s expense — but that changed Friday when it developed that Andrew himself may be back in corruption-buster Preet Bharara’s cross hairs.

And if not the governor, then certainly his alter-ego-cum-enforcer Joseph Percoco — a smart fellow who’s been tight as a tick with the Cuomo family since Mario was calling the shots a generation ago.

Those were the days.

Cuomo the Elder was center-stage, with Andrew at his right hand and Percoco — whom the current governor once described as “my father’s third son” — ever-present in the shadows. Meanwhile, an ambitious entrepreneur/academic named Alain Kaloyeros was beginning to make his mark in Albany — as was a youngish assemblyman named Sheldon Silver.

Both Cuomos, Kaloyeros, Silver and Percoco — among others — would collaborate to create a $43 billion nanotechnology empire. It would eventually include the State University Polytechnic Institute in Albany and participation in the current governor’s premier economic development project, the taxpayer-fueled, embarrassingly underperforming Buffalo Billion.

Fast forward to Friday, when it developed that Preet had dropped subpoenas on Cuomo’s office in connection with a months-long probe of the Buffalo Billion.

Suddenly Bharara’s interest in Bill de Blasio’s campaign-contribution shenanigans — the subject of an apparently Cuomo-inspired bombshell on April 22 — was last week’s news.

But while the mayor can be forgiven a secret smile, it best be brief. It’s hard to get off Bharara’s hook.

As Team Cuomo is discovering.

“This office has concluded that, absent any additional proof that may develop, there is insufficient evidence to prove a federal crime,” Bharara said of the governor in January, while wrapping up investigations that produced corruption convictions against Silver and former state Senate Majority Leader Dean Skelos.

So. Has additional proof developed?

It’s long been known that Bharara has been working on the Buffalo Billion — the number being the approximate number of taxpayer dollars Cuomo means to lavish on the city. It’s a complicated project, but — given Albany’s record — who would be surprised if a fat sack or two of cash had somehow fallen from the wagon?

Certainly not Bharara.

It seems that he’s particularly interested in Percoco, Kaloyeros, Buffalo developer (and big-bucks Cuomo contributor) Louis Ciminelli, lobbyist Todd Howe and a Buffalo-based construction company, based on last week’s reports.

Ominously for the governor, Bharara reportedly believes that Percoco — who resigned as Cuomo’s top aide in January — may not properly have reported tens of thousands of dollars in outside income that he and his wife received from companies doing business with the state.

Ominously, because while not a sparrow falls in Albany without Cuomo being aware of it, Percoco kept the sparrow census. That is, if Joe’s in trouble, no doubt Andrew is too.

Then toss Shelly Silver into the mix. At age 72, he’s looking at a minimum of 14 years in prison when he’s sentenced Tuesday — and he has every incentive to tell prosecutors everything he knows about a dubious project he helped create. Want to bet Bharara would listen?

The Buffalo Billion has always been more about politics than economics. The Queen City isn’t making a comeback absent fundamental, statewide tax and regulation reform — and even then the Albany Legislature would probably have to repeal winter. Who would want to live there?

But hundreds of millions of dollars have nevertheless been poured into — or committed to — the region. And there’s been very little meaningful oversight of the spending.

Until, maybe, now. Good hunting, Preet.