Dean was buzzing around the party, making the rounds to be friendly, though he was mostly just enjoying the turn-out for the fact the people were all here to celebrate Sam's birthday. Sure, he was used to waking up in motel rooms, in the bed across from Sam's, flinging a pillow at him and shouting "Rise and shine, birthday boy!" but it was nice to be able to throw a party for Sam. Hell, he hadn't even had a first birthday party.
A beer in his hand, he weaved amongst people and talked to as many people as he could, though every few minutes he was most certainly looking to ensure Sam was having a good day.
For all his smoke about getting Sam back, there wasn't a lot of fire. He just wanted Sam to have a good party.