Castiel wasn't sure why they were still talking about him with Sam being in some kind of trouble and Dean having the same look and body posture he had before he killed something that really irritated him, but they were some type of human themselves and therefore prone to fixate on things that were unimportant at the moment.
He watched Dinah and Dean, wondering a little bit about that. Dean didn't usually let people calm him down like that, but she was a woman. Maybe she was using her powers on him or something.
He continued to watch what was going on carefully, pulling back a little from the situation mentally and almost resuming the generic stare he usually wore when he was simply waiting.