Are Paul Krugman and David Brooks in a secret feud?

Jonathan Chait gathers the evidence that Krugman and Brooks have been planting their New York Times columns with implicit attacks on each other.

Chait concludes:

Brooks views Krugman as making himself a hero to the liberal choir, while he (Brooks) fearlessly challenges both sides. Krugman sees Brooks as residing comfortably within the cozy embrace of the conventional wisdom, whereas he (Krugman) risks being cast as a partisan or a radical by arbiters of respectability like Brooks for following the logic through to its conclusions. . . .

What makes the feud somewhat pathological is the Times' convention of keeping its columnists from openly debating each other. I suppose this is designed to advance the cause of civility. But the reality is that this just creates a lot of sniping, and the inability to quote and describe each others' arguments in any detail makes it impossible to treat them seriously.