My understanding is that only waterfowl get 'angel wing' from a diet too high in protein ... not chickens.
Can you tuck her feathers back under so they lay nicely? My 20 week old Barred Rock has one wing where the feathers like to lay out like that. It doesn't bother her, but it looks odd to me too. Occasionally I fix it for her, but when she moves around or jumps down from a log in the run and spreads her wings, it just goes right back.