Oh, he definitely has!
Sam’s learned to ignore it as best he can. He doesn’t want to go making Dean self-conscious with something they can’t help, and if Dean’s driving while he eats a quick bite, Sam wouldn’t want to be down on the seat of the car. Too unsafe for a guy too small for a guy who can’t wear a seatbelt.
Completely forced ignorance from Sam, knowing he’s not in any danger whatsoever. Occasionally losing his appetite.
Brothers Apart 