More details on Novak

The Chicago Tribune gives a number of reasons as to why Robert Novak may have decided to walk off the set of "Inside Politics" yesterday. In the meantime, CNN has reportedly suspended him "indefinitely." The second paragraph is key:

Novak may have been concerned about Ed Henry's plan to ask him about the CIA leak case, set in motion by one of his syndicated columns. But he responded to ribbing from fellow commentator James Carville with an eight-letter barnyard epithet and walked off the live mid-afternoon program before Henry could get to that subject.

Was it really about James Carville's comments or could you simply not handle the pressure, Novak?