Sam nodded at the apology. "Accepted," he agreed, keeping his eyes on the road. "Now. Tell me what, exactly, you are sorry for."

It's almost rote now. He can tell when Castiel is at the point where he needs to be taken down a peg, when he's acting out in the need for punishment. But Sam always makes him list his sins, the reasons why he needs to be punished this time, because he wants to be certain that Castiel understands why. And correct him when he thinks he's done certain things that need to be punished but which Sam doesn't consider worthy of it. It's all part of learning the difference between divine judgement and their relationship.