Hi. I just bought an 05 TD4 with 51250k miles on the clock. What concerns me is when I let the clutch up in lower gears or when I suddenly apply the accelerator, there is a bump and a feeling of movement toward the back of the car. The best way I can describe it is that it sounds like a big piece of luggage setting back under its own inertia - except there isn't anything loose back there that I'm aware of. You also don't feel it through the clutch pedal, which I'd expect if it was transmission related (I'm not very mechanical). Should I be worried?