Castiel's brow furrows slightly in confusion.

Dean is hiding behind bravado. Castiel knows enough to see that. He is just uncertain how to respond to it.

But he can see Dean's concern for the older man. He makes no move to stop him from going to him. In fact, he takes a step or two away to give him room.

Once Dean ascertains that the other man is fine, they can carry on. There is time enough for that.

Castiel idly shuffles through the notes and diagrams laid out on the makeshift table nearby, and gives Dean a moment.