Vibration at idle when warm

[Thurston]

Hi team, I'm a new member here. I have a 2007 D40 ST-X VQ40DE petrol. After driving for an hour, I come to a stop in D and have an unusual vibration on the drivetrain. Once in N or P vibration disappears. Had automatic "experts" look at it and they say everything is ok, by look they drove it around the block. Extremely smooth change can barely feel it.
Idle and everything else feels good...my thoughts are torque converter???