see here but an older car with more mileage
I have a new Torque Converter fitted by MB Dealer. Post fitting i have a slight vibration at times when at cruising speed. It presents as a slight tremble through the prop tunnel end to end of the car. Done so far: Torque converter and full adaptations by MB Dealer New engine mounts New...
forums.mbclub.co.uk
If there are reports of many new cars doing it, then I wouldn't imagine that dealers have had chance to work on new cars are make an error in reassembly