These things can just happen for no ostensible reason. I remember back in the early 70s a sherry glass that had been sitting on the serving hatch suddenly shattering into a cobweb of broken shards completely unprovoked. No one was near it at the time and the temperature was constant and there was no sunlight anywhere close to it. It's because these events are so rare that manufacturers know that the chances of a genuine claim are remote. It's a bummer, but I don't see a way around it.