Odd sleeping after playtime?

So I let my chinchillas out for playtime, and one of them always manages to get out of his play area, so i pick him up, tell him to stop, then put him back in the play area. immediately after he shoved his face in a corner, and went to sleep. He does this almost every time i scold him, or I put him back in his cage after playtime. Today, my other chinchilla did the same thing when I put her back in her cage, She's never done it before.
So do you think they're ill, sleepy, or just being brats?