Shattered Glass for no reason on my Samsung Galaxy SIII Phon

Sunday I was driving in my truck when I picked up a phone call (phone ok). Laid the phone down (phone still ok) until I parked. I got out of my truck put the phone in my back pocket (phone ok) walked into the house and laid it on the counter inside the front door (still ok). I was in the house for 40 minutes when I picked the phone back up it was completely shattered. There was only 4 of us in the house and we were all in the kitchen talking. I did not drop this phone, sit on this phone or do anything to this phone that would cause it to shatter. I went to Verizon where I purchased the phone and they told me that it looks like I smashed the phone. I have a hard case cover on my phone and it wraps around to the front of the glass and they said that that should have protected it, but I explained to them that I DID NOT smash my phone. They then explained that it could have been the change in the temperature, but my boyfriend was with me and his phone didn't shatter. They want me to pay $100 for a replacement, but I refuse to spend the money when I DID NOT do anything to this phone. I'm going to try and call Samsung about this but it sounds like I might be wasting my time. My boyfriend bought his phone the same day and has had no problems. I've never dropped my phone and I want to prove to them that I didn't. I mean if you drop a phone isn't there some type of damage done to the inside where I can prove there is none to mine?
Anyone out there never dropped there phone but it shattered for no reason?