Turbo lag wouldn't manifest itself as described above. I am not sure the car has a turbo fitted, I think it is the std FSI engine.
I would be interested to see what the fault code was that VW downloaded. Maybe you could find someone with VAG-COM to check it out before VW if the fault persists, then the VW community at large could get on the case too....
I would be looking at vwvortex.com to see if the fault has been reported by any owners in the states..
Gavin