Not at all surprising. I think the Edwardses were legitimately torn between the two candidates, but now they're adding one more voice to the wrap-it-up sentiment. One wonders if agenda-favors were promised by Obama — a special emphasis on poverty, a cabinet position, that kind of thing.
I hope so. Edwards played a hugely constructive role in this campaign on the policy side; realizing, perhaps earlier than the other candidates, that a strategy of stark departure from the Republicans was going to be a winner — not to mention downright necessary. It would be great to see him as part of an Obama administration, though I could imagine the Edwards' staying as public gadflies on poverty and health care.
Anyway, I think it's a fine choice.