You can Google around and find out information on your turtle. Once you
are aware of it's natural habits, you can determine if it's behavior is
normal. You may even find out you have a protected/red-listed species.
In that case, call your local wildlife department and let them know.
They keep tabs on these things.

FWIW, it's often illegal to bother wildlife. About the only time you're
allowed to touch them is to keep them out of harm's way. Say, keeping
them out of the street. I agree with Kathy, let turtle be turtle. I'm
pretty sure s/he knows how to take care of themselves.

Lilly