I'm at nearly 400 K ( actually I think 399990miles) and I have a sound ... not sure it is DMF or not since I had a slight throwout bearing noise starting to happen occasionally ( I have not driven the car recently because of it .... Ill save the last 90 mile trip to the TDI guru to look at when he gets time)
Having said that, I am fully prepared to swap stuff out if needed and most likely fairly soon since mechanical noises don't normally cure themselves in a good way.
If you aren't hearing anything funny , I would be inclined to just motor on a bit more but thats just me...