I was in an apple store recently to get my iPhone 4 replaced due to a dodgy home button, while I was in the queue a lady came in with an iPhone with a front shattered screen claiming that it was in her pocket and shattered when her dog jumped up at her.
The apple employee explained to her that it should be very difficult to smash the screen like that, unless it suffered significant impact, which they would be able to tell by other means.
She had owned the phone for almost a year and had no apple care, but he apologised to her, happily replaced her phone and gave her a free case!
Might be worth asking