I'd be really surprised if the top mount was damaged while driving.
I'd be less surprised if they damaged the new one while re-assembling the strut assembly, and threw it on the car anyhow.
@AZP - One thing I've noticed is the dealers push a LOT of extra shit in the 30k/60k/90k/etc maintenances. Things that Subaru doesn't recommend. Additionally, they tend to leave things out that I personally feel SHOULD be done (inspect and top off transmission fluid instead of replace it, etc).
If you go by the dealer service menu, you probably got screwed.