Yeah I didn't think I had any until someone posted a pic. My copy of Portal 2 has 2 small chips in it that don't affect gameplay. Makes me wonder if it wears out the disc drive faster than a normal disc though. It's not going to be something most people will notice unless they know what they're looking for.
I wouldn't think so. The edges of the disc don't contact anything during use... I suppose it would have a very minute effect on the balance of the disc, which would only effect the spindle motor. Having worked on dozens of 360 DVD drives, I've never seen a spindle motor wear out.