2007 Santa Fe GLS 2.7 V6. T belt replaced by dealer at 62K. Noticed engine vibration when picked up vehicle. RPM is steady, engine runs smooth, no error codes, no strange noises. Mechanic who did the work confirmed vibration problem and recommended bringing it back - had no answer on the cause but mentioned lose motor mounts which I doubt - the car ran perfect until the dealer did the work. Any ideas/recommendations on the cause/fix?