I Have a X720. Love the tractor. I only have put about 11 hous on it since purchase a few months ago. I mow about 3 acres with the blade cut height at 2.5 inches. Relatively flat or gently sloping land. The belt just broke on the mower deck. Is this common. What could have caused this. I didnt hit anything. I was mowing fine. I then lifted the deck and drove about 50 feet to another spot an put the deck back down and turned the mower on. Loud snap nose. The belt seems to be broken. Should this be covered under warranty? I assume these belts are made to last longer then 11 hours?