I have exactly the same on my MW E92.
I dont regard it as acceptable, but could not be bothered to reject the car, reasoning that I would not notice after a while (I kind of don't, now, but it is winter, dark and the car is more often dirty than clean). Also I had waited 9 weeks for it to be built and that seemed like a long time...
Given that several other MW owners have mentioned the same thing, I wonder if their distribution of these imperfections was the same as mine?
All on the front left corner (front left wing and corner of bonnet).
If these imperfections were evenly distributed all over the car I would be more inclined to think that they are "normal" but a cluster in one area suggests otherwise.
And I had nothing like this on my earlier (2007 build) E92, in Sparkling Graphite.