What statements?
I don't remember any such statements.
I was thinking of Dick Cheney alluding to the mystery of the anthrax source on Meet the Press (or one of those news interview shows), or Colin Powell showing the vial of faux anthrax at the UN. Now, those statements admittedly had other purposes (Cheney was showing the need for pre-emptive strikes because you couldn't tell who the perpetrator of an attack was any more, and Powell was trying to demonstrate graphically what Saddam Hussein could do with the anthrax that he was thought to have stockpiled). But they must have known that those following the anthrax affair would wonder if those statements were hints. Cheney in particular left an impression with me like the Cheshire Cat.
Moreover, the whole WMD argument was bolstered psychologically by the fact that the anthrax mailer had not yet been discovered and could have been Iraq.
Anyway, this was a minor comment. I thought Treble Rebel's observation was quite interesting -- that the FBI would have looked very bad if there had been a large follow-up attack that al-Qaeda took responsibility for, and that therefore the FBI must have been quite confident that such an attack wasn't going to happen.