Originally Posted by ChrisCC
to be honest this is a little hard to believe. I've owned all iterations of the iphone and ive yet to experience a self-cracking screen. Maybe you bumped into something? Regardless even if it was a defective unit and the glass had a weak point its going to be hard to prove that the genius at the apple store. hopefully things work out for you and you can get a replacement
I have been a long time iPhone user (original iPhone, 3GS, 4, 4S) and it is the first time the screen has ever cracked. I did sit on it few times, but only against soft seats, which I am sure most of us do regularly. I suppose it has been dropped from a sofa to soft carpeted floor few times (although not within the last week or so) but my iPhone 5 is in a case and that is also something that shouldn't cause screen to crack.
In any case, I will be stopping by the store in few minutes.