Hope you don't mind me adding my issue here to this thread since my problem is also related.
On the 29th of May, I sent in my iMac for repair at Eaton here in Toronto (covered by warranty). The issue I had with my display was discolouration. They got it all fixed and I came and picked up today. BUT... I didn't check the display for any crack whatsoever. Everything happened very quick because I trusted their expertise and didn't bother to carefully check the screen. Once I brought it home, immediately I noticed a small circular crack on the black area of the display, lost a tiny piece of glass from the display. I didn't bang the iMac against anything. People are very careful with their stuff when an item is that expensive. I don't want to blame the one who assembled the display or the one carrying it out from the storage room, either way I do not know how that crack got there. In some way it's really my fault for not having a careful look while at the store. Personally, I don't mind using it with this crack, but it's kind of distracting because there's a bit of reflection. Any suggestion on what I can do?