Does my 4yr. old have trouble letting go??

So this is what I found one night when I went to put Claire in bed. The lights were out and I was getting ready to lay her down when I about jumped out of my skin. After realizing what was in her bed, I of course, had to grab the camera. Maddox begs to sleep in Mason's room every night. The problem is that Mason has school the next day. So he was begging and begging.... (irritated) I said, "Maddox, you can sleep anywhere else in the house, just not in Mason's room." Well, he thought long and hard about that.