Thank you! I've never noticed it before. Maybe he's just maturing? I did notice some little bugs in his enclosure Does that ever happen to any of you guys? I moved him into a temporary enclosure and I'm going to purchase a new one for him. I've had him in a glass tank and its hard as hell to keep it humid.
Tiny bugs are normal because they often reside in the soil. If they become a problem, try replacing the soil. I've heard of some people baking it before placing it in the enclosure.
Expect to see many changes with your red's skin and shell. My red began developing marbeling on his plastron when he was a year old. I thought briefly it might be shell rot, but he's just developing a lovely pattern.