I don't think it's a big deal. As the game ended, the celebration started, and i don't even know if he could have found Brees.
Manning did talk after the game, so i don't see it as a big deal.
Yes, it would have been nice to see him seek out Brees, but he may have figured it was Bree's time in the sun, and just let him enjoy it.
Or he might have been a jerk. LOL!
The only one that knows is Manning.