it's those damn knomes that roam the night, looking for cars to steal. They steal your car, and purposely disengage the ABS just so that can slam the brakes and put flat spots on your tires....it's a proven fact....ok, just kidding, but honestly, how much vibration are we looking at? If its major, it may be your struts, if its just minor vibrations here and there, I wouldn't worry too much.