Is there any chance the subframe was not bolted tight? This sounds like the type of failure the subframe is supposed to stop. I found loose bolts on the front end of my tractor when it was new and I'm sure that can happen on other tractors in other places.
Whatever the reason, you haven't mentioned warranty (that I remember) and I hope you are covered. As a second backup, if you had insurance on the tractor, that would surely cover anything not covered under warranty. Good luck!