My bike's only about 2 weeks old, with less than 300 miles; I was riding today and noticed a loud rattle from my rear drivetrain when I was on rough roads. I rode home with no real issues and began to investigate. I found that my freewheel was loose, and took it to the only shop in town still open @ 6pm on a Sunday. They tightened it down but told me my freehub is blown. Anyone have experience with this problem on a 105 10sp cassette? Should this be under warranty?