I have those too on both sides near the battery. They have been there since the first day I had mine. They are seams where the plastic is put together (a very poor fit at that). The original poster has a crack that extends into the upper shell. This one appears to be somewhat normal from how mine looks. If you follow it around with a light, you can see it goes along a seam with a straight line at the battery compartment.
I am curious if others do not have them in that exact spot
