Whether intentional or not, Libby has lied, the real question is if he did it intentionally, why? We have more or less learned Plame was not covert so there could have been no outing, but did Libby know this and was he just afraid he might have?
It was just the stupidest thing to do, it's always the cover up that gets them and in this case a cover up of something that wasn't even a crime.
I think Fitz is fishing, he's just changing lure's now.
If the testimony as set forth in the GJ was accurate, Libby could either admit that he disseminated classified information to reporters, or lie and hope he didn't get caught. Looks like he stupidly chose the latter course of action.
If you haven't read the indictment, it is quite plain to anyone with a little common sense that Libby knew the information was classified. And that information comes from other WH witnesses, not reporters. The obvious answer to your question is THAT'S why he lied about it. He knew he did wrong (I'm not saying here he violated IIPA - but revealing classified info to reporters for political reasons is WRONG. If you want to take issue with that assertion, have at it. I hope you do.), so he tried to cover it up. Like a 5 year old.