My 2010 S550 has Dynamic/Massage seats. When the massage unit is turned on, there is a short whirring/buzzing noise in both seats that cycles on and off every 10 seconds or so. Obviously it's the mechanism in the seats. But I have had my car 6 months and don't recall hearing the noises when the seat massage was turned on before. Today it was loud enough to hear with the engine and radio turned on. Anyone know if the noises are normal? Seems like it should be dead quiet.