No, from your pics I do not see any signs of angel wing. That is my interpretation of the photos and I am not a vet. Are you talking about the prominent feathers emerging on the wings? If so, those just look to me like blood feathers, aka growing feathers with a significant blood supply going to them. The flight feathers can look quite prominent when they are in that stage.
As far as the 28% protein, I would not feed it. My experience with my ducks is that it is not a good idea. Whenever I have fed a higher protein feed (and not even as high as 28%), problems have developed. It is not just angel wing that may be a problem with higher protein. When I tried a 24% starter, I had a few birds that died with no symptoms (possibly kidney problems?) and a couple that developed roached backs. When I have fed lower protein, I have not had any of these issues.
Of course, these are my personal observations, not a scientific study. The ultimate best way to raise waterfowl, in my opinion, is to give them as much space as possible and an extremely varied diet. Ducks that are allowed to free range and forage almost always seem to be in the best condition.