Twisted feathers in older duck

[Von Blumenthal]

Hello! My 4 year old Swedish Black has sprouted a couple twisted feathers on each wing. At first I thought they were molting and coming out weird but upon further inspection they appear new! She is otherwise healthy and receives a diet of Mazuri Waterfowl pellets and fresh greens about once a week or so. I don't believe this could be angel wing, due to her age, and her wing shape seems fine. Could this be an indication of some other issue? Or just some feathers on the fritz?

Thanks!
-Von

 

[sourland]

Upon rare occasions I have had adult birds develop a very slight wing problem almost like angel wing ?