We purchased an IPad 4 11 days ago and on the 5th day the screen broke up on the edge at exactly the point where the thumb is placed to hold the IPad. The glass broke up with a random crazed pattern and then since has developed 2 longer cracks and now small pieces have fallen out. I have taken the device back to Apple and they despute the fact that the glass was imperfect and that something must have dropped onto it. Nothing has been dropped onto it. They have agreed that it has not been dropped. They will not replace or repair the device under warranty at present. Can you tell me if this is a common fault with the glass?