8 yr old wearing baby clothes

Help!! Is it normal for my 8 year old son to want to wear baby clothes? Recently he's been asking me to buy baby clothes and diapers for his stuffed animals. He has tons and still plays with them. (He is on medicine for adhd and has always worn pull-ups. We just recently got medicine for his bladder problem so hopefully we'll get rid of those for good!)  BUT I've been catching him secretly putting on these baby clothes. He always acts guilty whenever I come into the room and I'm afraid I don't handle it very well. Why would he want to do this? Does it have anything to do with him wearing pull-ups? He also spends a lot of time in the bathroom and usually manages to get poopy on his hands. Sometimes he wipes it on my rug thinking I won't notice. Other times he spends forever washing his hands. He is a very sweet, smart child. Does great in school-top of his class. He is the baby of the family and I worry that I've babied him too much. Help! Is this normal?