Reliable and well-maintained 130k SEAT Toledo Tdi with reconditioned dsg gearbox has sound like metal keys lightly jangling up through transmission when accelerating and changing up in auto mode, probably more often from stopped or low speed. Noise stops after change then does not come back when driving. Doesn't happen on down change. Seemingly DMF and clutches okay. Mainly happens in colder weather. Happened 3 years ago and it went away. Any ideas what it is? BTW, the car drives really well and the changes are fast and smooth...