Seriously if I was the manufacturer? I would tell you to fly a kite. Glass doesn't crack by itself.
Sorry mate, but I think you have to go buy yourself a new one. Or investigate "Who Did It?". As many others here have highlighted, it seems to be more probable that someone else in your home might have broke it accidentally. Or you yourself while cleaning.
It also seems highly unlikely that your home will experience enough sudden hot-cold temperature changes to cause glass to crack.
Glass can be weakened if there are impurities in it and crack easily.
I'd just hazard a chance and write to them to tell them about it and ask for a replacement. It's a long shot, but e-mails cost you nothing besides 5 min of your time.