I've used and tuned on a fair few hub dynos, and with tuned small capacity single turbo engines I always used to get that annoying torque spike, have seen it a fair few times with the tfsi.
Look at this link of a place that uses a hub dyno:
http://torquetronix.co.uk/media-news/94-dyno-plots.htmlThe majority have a similar torque spike, so nothing to really worry about. It's also the main reason I went with a 4wd DD chassis dyno when I was dyno shopping.
Hurdy, if you are ever up this way pop in for a dyno test, considering an R for my next car