I thought the same thing but read, recently and I forget where, that Russert said they DID discuss Plame but hey, I could be wrong. Give me some time to figure where I read this as I was surprised too.
I saw Russert, on the air, talk about this issue. He coyly said that they didn't discuss "the name Plame". He did not deny talking about the general subject. In fact, I believe he inferred that the subject was discussed. I don't recall the time, or the place of Russert's statements. I believe it was on the air a year, or so, ago, but it might have been longer.