You can tell the skin around it is very dull colored while the red area is not. So I'm thinking he's about to shed but that area has already shed. How long have you had her?
It honestly didn't look like anything bad.. just cosmetic.
The only thing comparable I had was reddening around my dragon's tail shed, and he shed the next day and the red was gone. You can see it in the middle of his tail in this photo.