In my experience your detailer is right on - cars that are hand painted/test driven at the factory almost invariably show up with buffer trails, sanding scratches, dust nibs, etc. We did quite a few new car preps for Lambo of Toronto and (if it makes you guys feel any better
) they arrived in much worse condition than the McLarens we've worked on.
The MCs may have had da sanding marks and some holograms but at least the paint was very consistent and the finish was nice, so when the issues were corrected they were bangin'.
FWIW, I think the primary issue is that the guys at the factory are working on un-cured paint. They almost always "detail" the car after spray but before baking, so they have to deal with shrinkage, filling, etc. A good example is this: http://gtaindetail.com/mclaren/luke/12.JPG
That was after we removed the factory installed clear film - it must be applied after baking but before final detailing, which would example the crazy buffer trail.
In any event, you're all sorted out now. Looks amazing!