SAM SAYS BOO.
He wanted to do more. He wanted to pick her up, carry her back into her apartment, and have away with it. So badly that it wasn't even something worth laughing over. Rather than doing as much, Sam went against every emotion in him, only listening to that one little voice of reason, and carefully wrenched his mouth away from her own. Then he took a step back, shot Heather a smug sort of look, and said, "And don't you forget it."
He certainly wasn't going to. And he wasn't going to forget the fact that he just broke about every single rule that he'd set for himself and Heather since he'd figured out that he liked her. Great.