My Deere D110 lawn tractor's engine "blew" a head ...

My Deere D110 lawn tractor's engine "blew" a head gasket after 50 hours of use. It also was only purchased in April 2012! All periodic maintenance was performed. Briggs & Stratton refused to pay for all repair cost, saying it was not covered. They also admitted the bolts now had to be torqued to 250 psi vs. the factory specification of 220 psi. Does this mean they knew there was a manufacturer's defect, and didn't alert its customers? My product is also registered. John Deere states their equipment is made in the USA - well I'm an American veteran and this is a disgrace.. My previous Snapper tractor, now Torro, continued working after 25 years.