Hmm, I fully understand why your suspicious of the garage! If you had of driven over something then I would argue tracking would be out, buckled wheel, broken suspension components, broken under tray etc, etc. I would like to think that you would get some factory (manufacturer) good will as it's a part that shouldn't have gone wrong in my opinion.
That's what we used to get customers when I worked at a Volkswagen service department.
Cheers
Steve