Mentioning the ice cream had mostly been for Sam... it'd be just as funny for him to hear Bobby bitch to Dean about it--and she kinda deserved it after that joke earlier!

He realized quick she was asleep and deep enough she didn't even start at the sound of the door... well, then, he was just going to quietly undress, turn off the lights in the room and settle in as well. No sense in waking her up if she was sleeping easy.