I have had this mbp a little over a year, i don't baby it but its pretty mint. After having my trackpad replaced by apple recently i decided to just look at the body and i notice a hair like crack at the hinge area. The area is not isolated and it doesn't move so i don't understand what could have happened. I have never dropped or banged it. I have attached a pic below. Is this by any chance covered by applecare? And could it have been caused by heat? 
