i wish i knew his thought process

because he is so darn cute
Tonight after bath we put Lance in a diaper and pjs (bottoms and tops). After finishing the movie we started last night we headed upstairs for bed. He climbed up onto our bed while I went into the bathroom to get ready for bed.
While I was in the bathroom I heard him remove the tabs of his diaper. I asked him what he was doing, but I got no response, I just figured we put the diaper on too tight and he was adjusting it. After finishing up I walk into our bedroom and I discover Lance asleep in our bed with his thomas underwear on.
While I was in the bathroom he removed his pajama bottoms, taken off his diaper, put on his underwear, moved a pillow to the end of the bed (his spot in our bed), covered up with a towel (the only thing close to a blanket around) and fallen asleep. Too cute, he loves his thomas underwear!
So now I have a decision to make, do I keep on the underwear and risk an accident or do I try and put the diaper back on and hope he doesn't wake back up?