In case you didn’t hear, Robert Novak cursed on-air and then stormed off the set of CNN’s Inside Politics during Thursday’s show.

If you watch the clip (here on iFilm.com), it looks like Bob got pissed at James Carville’s zingers. But if you’ve ever seen CNN’s kaput Crossfire, you figure that Bob has taken — and dished — a lot worse. So why did Novak drop a BS-bomb and walk off? I suspected that it had something to do with the Valerie Plame business.

But it still didn’t explain why Bob chose that moment to flip out. Then I read an article in yesterday’s USA Today, which seems to wrap everything up in a neat little bow.

Last week in his column, Novak wrote of the outed CIA operative that “she could be identified as ‘Valerie Plame’ by reading her husband’s entry in ‘Who’s Who in America.'” Again, if you watch the clip, you’ll see a large book sitting on the desk. It’s a copy of “Who’s Who in America.” The theory here is that Ed Henry, host of Inside Politics, planned on questioning Novak about his column, his involvement in the Valerie Plame mess, etc. Novak saw the book and decided he wasn’t going to deal with the Plame story. He decided he wasn’t even going to give Ed Henry the chance to ask him about it. So during discussion about Katherine Harris’s Senate bid, Bob decided to get huffy and walk out.

I wrote about Karl Rove a few weeks ago, and ultimately I believe that Rove leaked Plame’s identity to Novak, who was more than happy to do the White House’s dirty work. I don’t know if Novak will ever face jail time for this, or be forced to give up his source. I don’t know if Karl Rove will lose his job over this. But it would be poetic justice if jailed New York Times reporter Judith Miller gets out of jail to see her career flourish based on her integrity, while Novak gets drummed out of television. On the other side of coin, a reporter doing time to protect her source strengthens the freedom of the press and more importantly, the notion that we live in a free and open democracy — while a talking head like Novak proves once again (see: Armstrong Williams) that getting in bed with subject matter you’re supposed to cover objectively can cost you your credibility.