Hillary Clinton grew irritated during a recent PBS interview when she was asked about her husband's infamous tarmac meeting last year with then-Attorney General Loretta Lynch, saying she does not buy the notion that it was a costly error.

Bill Clinton and Lynch privately met last summer on her airplane in the midst of the federal investigation into Clinton's private email server use. The two claimed the meeting was innocuous, but the summit raised concerns about the impartiality of the Justice Department.

PBS host Judy Woodruff noted then-FBI Director James Comey's testimony that the tarmac meeting made him believe the Justice Department could not "credibly complete" the investigation, starting the chain of events that ultimately led to his late-October letter to Congress reopening the email probe.

Clinton has called the letter determinative in her loss to Donald Trump.

"So, my question is, to what extent did Loretta Lynch and President Clinton make a costly mistake?" Woodruff asked.