Here's another thought.....maybe he really enjoys his "punishment" and therefore tends to "act-out" the bad-boy part so that you will "handle" it later on???
Not to add to the mix but part of the MLC equation states that they begin to act like children. His moodiness could be an extension of this and his replay of old antics, before making his "final" decision to stay? Maybe it's the release of them and closing the door???? (what do I know just from reading books??) Just some thoughts for you.... Tootles............