I just got my XTI last night, and i had it sitting on my desk. Well i walked past it, and the shoulder strap caught on to my hand, and knocked the camera right off the desk!! It appears to have landed on the upper right hand corner pf the camera, based on a small smudge in that area. It still takes photos fine, everything appears to be working fine. Is this something i should worry about? Could this have caused any damage? How sturdy are these cameras?