Concerned about Franklin's shell

[Jessica5]

Hi all,

I am concerned about my tortoise Franklin's shell. He is very active and is constantly moving around his cage. He has a few obstacles in his case including drift wood, a wood log, fake plants, rocks, and a course basking rock. I am wondering if this is caused from him rubbing his shell on the obstacles in his cage or if it is something I should be concerned about.

Thanks!

Jessica