Vibration Or Something More Serious

[oohpapi44]

Ok, I've heard everyone speak of the vibration problem that's common with Lexus. Now since I'm a newbie to the Lexus Family with my 01 GS430 here's my question. What does the vibration feel like and is it only a 60mph thing? There is a vibration under my foot (floor panel) I feel when travelling (haven't paid attention to the speed correlation yet) and feels like a slight grinding/rubbing of the rotor. Is this the same common problem or should I be taking it back to the dealer... My issue is that the car was definitely hit before and the front left quarter panel is not original so any advice to alleviate unnecessary worries (or advice telling me to worry) would be appreciated.

[TurboGS300]

Could be the caliper sticking. Check it out before it does more damage <_<