I'm not convinced. I will have to see if it develops more, or remains like that. If you look at her all black hen, she has a couple of tail feathers like that. I also have a few hens with a couple of slightly curved tail feathers - but they aren't to the full extent of a roosters. If they get more curved and longer...OR if s/he gets drapey 'rump' feathers at the base of the tail, then yes. At this point, though - it could be nothing or it could be the beginning....again, wait and see if it develops more or not. Presently no 'worse' than some of my hens. And the saddle feathers are still quite rounded at this point, instead of the drapey pointed roo feathers.
(Okay, so 'drapey' is a word I've made up recently. I have used it quite a bit over the last year or so. How do you all think it should be spelt? 'Drapey', Drapie" or Drapy' - I kind of thing the last would be pronounced 'drap - ee' with a soft a, ????)