If that's the fix then I am curious if this happens with the HVAC on recirc or when it's set to outside air? Sounds like air causing a seal to vibrate. This would lead me to wonder if the two vents behind the rear windows are not venting properly (if they are vents like on my other cars) and the cabin is building pressure forcing air past the seal. Probably happens on the drivers door first since that door is opened and closed the most...?
