MacBook Pro Display Issue
I would say you should not be worried however since you do have Apple Care I'd backup your files using Time Machine and then make arrangements to have it looked at and repaired.  As to whether or not they can fix it or just replace the part(s) in question that will be decide by Apple however since it's under warranty the'll have to fix it or replace it.

From Contact Apple Support ...


  A Genius Bar reservation is an easy way to get hardware repairs, but
  we can solve many issues over the phone or by chat. Tell us a little
  about what’s going on and we’ll suggest the right support option.