Sam should definitely punish him. It's the obvious answer, one that has Castiel's body already humming in anticipation. A shiver runs down his spine. He may have overstepped the line he merely meant to toe - but really, in general, it's always worth it.

The truth is that Castiel needs to be punished, sometimes. It's how Heaven used to work - do wrong, be punished. All his punishments in more recent years have been self-inflicted. To be punished for a transgression like this, it restores a balance inside Castiel he missed.

"I'm sorry, Sam."

And he really is. But he needs the reassurance of a punishment, occasionally. Tonight is such a night. He just needs to be reminded that the rules are in place, and the leash isn't dangling loose.