Apple places a 90 day service warranty on all parts, including ones supplied to AASPs. Why does everyone assume all AASPs are these dodgy, horrible con artists? I'm trying my best here.
Seriously though, find a reputable AASP and you should be fine.Also, I can confirm that the issue is mostly where the plastic posts/strips above the LCD contact the Top Case when closed. Sometimes the Top Case can crack for other reasons (I have seen ones with cracks along each side rather than at the front) but it's almost always where those posts make contact.