Leopard gecko got out and I found him. But now he's acting different?

Question

I had my leopard gecko for about 2 years. I got him from a friend who was moving. Anyways I woke up and his lid was halfway off so I checked on him. He was gone. I think my son got him out without permission and didn't put him back. (They only are supposed to be handled if I'm right there) well after I found him in a little box that has a opening under my bed I set up. Now he won't eat his meal worms or crickets. Barely anything only thing he eats now is dubia Roaches. Not only is he eating different but he likes to stay only on his cool side. I rarely ever see him on the warm spot. He's about 5 or 4 years old. He's big for a leopard gecko. He likes to stay in the cold. He's not aggressive and loves to snuggle. Pooping is normal