[BigBobber]

You wrote: "The FBI was monitoring his emails written when he was still on active duty."

That does not appear to be correct. According to the NYTimes:

Government officials said that the F.B.I. began an investigation into a “potential criminal matter” several months ago that was not focused on Mr. Petraeus. In the course of their inquiry into whether a computer used by Mr. Petraeus had been compromised, agents discovered evidence of the relationship as well as other security concerns. About two weeks ago, F.B.I. agents met with Mr. Petraeus to discuss the investigation.

Petraeus resigned from the Army on August 31, 2011.

So this means he the affair, resigned from the Army to take the CIA position, knowing he had had a recent affair. Then "someone" notified the FBI to start looking at his e-mails "several months ago". Several months ago like September 12, 2012. Get the drift?

Finally, this gem from the AP

Morell rather than Petraeus now is expected to testify at closed congressional briefings next week on the assault on the consulate in Benghazi, which occurred on the 11th anniversary of the 9/11 attacks.

[RoosterRedux]

I might be wrong, but I had the impression that the emails were written when he was still on active duty but the investigation was recent.

[RoosterRedux]

Actually, I also recall hearing that she broke off the relation as he was about to leave the army and then he followed-up by continuing to send a flurry of emails after the break-up.

So he may have already started at CIA when these emails continued. This would be the source of the statement that the FBI was concerned that she had access to his CIA email account.