Now I understand what you were saying, yes it would be normal, it's just the same as pulling off in 1st gear without using the throttle which is very common with a diesel car - loads of torque plus the fuelling is different to petrol which is why you can't do the same thing in a petrol.
Driving in 6th gear at 30 mph is not the sort of thing you should be doing, you have no reserve for slowing down except to stall the engine, hence your comment that it continues driving, if I was you I would select a better gear. :thumbup:
Rob.