Zafira 2.0Dti valve noise?

I have just purchased a 53 plate Zafira 2.0 Dti with 30K miles on the clock. I have driven a mondeo 1.8TD for the past 6 years and the vauxhall diesel sounds crude in comparison.
I assume that it is a characteristic of this unit.

Anyway, my question...

When I start the engine from cold (15 to 20DegC), there has been a few occasions where I am half a mile down the road travelling at a constant speed, and the engine makes a valve sound which goes away after a couple of miles.
Pressing the accelerator during this warm up period sometimes seems to make it occur.

Is this unit capable of advancing it's timing when cold and accelerating and is this anything to be concerned about ?

ps The engine just seems to emit more valve noise in comparision to my mondeo 1.8td (8v)...maybe its those extra 8 valves !