Hi Andy - yes there is some truth in what you have been told. Whilst the 7k warning is there the engine has not yet come up to temperature and the ECU is in start up mode. The softwsre for this mode is not perfected it seems (but who am I to suggest how the ECU is programmed), you will find that the running in this mode is occasionally lumpy, as has been commented on before. It seems like the ECU almost overfuels the FSI system as far as I can tell. As a result if you don't let the car reach temperature and go into normal running mode and switch off before, there is a tendancy to fowl the plugs. That is why the dealers tend to change the plugs at PDI, as you can be sure that the delivery drivers dealship staff would be the last people to pay any attention to advice such as you have been given. Apparently there has been a software upgrade that some have mentioned to try and alleviate this, your car may have this already, I was going to ask when mine goes in for service.
I have had one episode when the car appeared to be running on 7 cylinders for a short while, this followed a couple of short starts to move the car around the drive / garage. It quickly cleared by taking the car for a short run allowing full temp to be reached. It sounds like that may have affected djcevo the other day too - see his thread:
http://www.rs246.com/index.php?name=PNp ... ic&t=58186
Certainly now if I start the car even for washing and move it out the garage I let it run to get up to temperature if I can