Odd sound of gas-giving

Hello, I came home a bit worried today. And I noticed that something in the front (probably engine room or even the engine itself) rattles pretty much after the gas-give. If I let it really turn up to about 3000 upm zb. and then walk away from the gas, the ratter stays the longest, about 3-4 seconds. Then everything is normal again and the engine runs quiet. I wanted to find out exactly where it comes from, but as soon as I am in front of the car it is gone again^^ So the course is: giving gas – gas away – an eyelash after the speed is again idle starts for 1-4 seconds the ratter (depending on how high I had it turned before). I have never noticed the noise before, therefore I am particularly worried now. For clarification I made a recording and attached here. Most clearly you can hear it at the end of the recording. Data: Phaeton V10 TDI, almost 140 tkm, service in 400 km. (Here a short 2nd question: Is it particularly bad when I refer to the service of 6 km. I really can’t express my greetings to Vienna.