Sam had to concede that point, with a wry expression a slight tilt of his head. Dean didn't say much about anything that really mattered. The fact that Dean hadn't said anything to Cas about it didn't mean anything, especially considering the fact that Cas was also from the past from Dean's point of view.
But there was something else. Sam had been trying to tell himself that nothing was wrong, that things were just different, and he almost believed it-- because he was very good at lying to himself.
The instant that Cas said something about it, however, all those nagging doubts came back. Somehow, he just knew that they had noticed the same thing, and if it was a new change even for Cas, who was farther ahead of Sam in the timeline... then maybe he wasn't just imagining things. Maybe there really was something going on.
"That he's... different?" he asked. "Yeah. I thought... maybe it was just because of how much time had passed... but he's not as far ahead of you, is he?"