Sounds very similar to what happened to a friend's bike. It was also quite new (~ 3 months) and had been serviced at the LBS where he bought it. His warranty claim was initially denied, but that decision was reversed when he pointed out that:
- the bike was almost new and had no modifications
- had only been maintained by the LBS (an authorized Trek dealer)
- he and his wife had bought a number of new Trek bikes in the last few years.

He was scheduled to receive his replacement bike today - don't know if that happened yet or not. AFAIK he still doesn't know exactly what initiated the failure.