On a Players only show on NFLN Friday before the Super Bowl, they discussed how they each handled it, and they all had different ways of handling the longer halftime. Irving said that he went back to the locker, the coaches said their thing, then there was like 15 minutes or so left and he went out to the tunnel and watched Michael Jackson perform. I think it was Sapp who said he went to sleep and Warner had said that he had a back issue one of the super bowls, and laid on the training table and told people to leave him alone but let him know when it was time to get back out there.
So I'd say with that knowledge, this isn't really weird at all.