Sam did not find Norman ridiculous. He thought he was inherently dangerous, sort of like the vampires that could look like everyone else right until they tore your throat out. Sam wasn't interested in being understanding about Hitchcock's commentary on split-personalities and psychological trauma when he was in the damn movie. (He glanced at his hands, now pasty grey.)
His eyes came down to the note in Fred's hands, and his expression only indicated that he'd seen it before his attention went back to Norman's face. He was trying not to be challenging about it, but he had some difficulty hiding his wariness of the man.
"Family stuff," he added to Fred's statement. The Winchester pride wasn't insulted by admitting their dedication to each other.