I have no idea .. it could be that he didn't recall... I guess it depends on what Libby actually said
My point is, if he did not deliberately lie, then he should not be charged with lying. And from what has been reported, that his notes said one thing and he said something else, I don't see how it was deliberate. Misremebering something is not a crime (last time I checked, anyway).
misremebering = misremembering