Hillary Clinton. Drew Angerer/Getty Images

As fired FBI Director James Comey testified Thursday mostly on his conversations and communications with President Donald Trump, he revealed one bit of major news unrelated to the growing investigations involving the White House.

And a law professor says that looking back, the incident could have changed the course of last year's presidential election.

Comey said during testimony before the Senate Intelligence Committee that Loretta Lynch, the attorney general during the FBI's investigation into Democratic presidential nominee Hillary Clinton's private email server, had asked him to refer to the inquiry as a "matter" instead of an "investigation."

Comey recalled the request giving him "a queasy feeling." It also echoed language the Clinton campaign itself was using.

"That was one of the bricks in the load that led me to conclude I have to step away from the department if we're to close this case credibly," Comey said.

After hearing Comey's Thursday remarks, Jed Shugerman, a law professor at Fordham University, said he could no longer "stand by my earlier criticism that the GOP was asking about Clinton email to distract from the Trump questions."

"They may have intended to change the subject, but they found a real subject to investigate further," he added in an email to Business Insider.

The professor called the apparent pressuring of Comey to use "matter" instead of "investigation" a "huge mistake" and "a partisan intrusion" on Lynch's part.

It "probably changed history by making Comey more skeptical about her and the Clintons' role," he said. "I inferred that it had an effect on Comey that may have changed how he handled the investigation later. She will face very tough questions. And it validates the follow-up questions on the Clinton campaign on their handling the email."

"We will hear a lot about this," he added. "It does not rise to obstruction, because it was wording/semantic, not the substance of investigation, but Comey was right to be troubled. Lynch and Bill Clinton should be called to testify and explain their behavior. What's obstruction for the goose is obstruction for the gander."

Comey gave a press conference early last July announcing his recommendation that the Justice Department not bring charges against Clinton, though he painted Clinton and her team as "extremely careless."

In late October, in a sensitive moment for the November election, Comey sent a letter to Congress announcing the discovery of new emails that may have been related to the Clinton case. But days later, after early voting had begun, he announced that the new emails, which were found on disgraced former Rep. Anthony Weiner's computer, did not warrant further investigation.

Comey originally felt the need to deliver that July press conference after former President Bill Clinton was found to have met with Lynch aboard a plane on a tarmac in Arizona.