Hmm that is interesting! I don't know if I would say recessive pied, but possibly! Julio has a feather on his back that has a "v" shape on it, he molted it out a few months ago and one grew back in just the same!
I wouldn't say recessive pied, since pied mutations remove body colour, so one or two coloured feathers wouldn't be an indicator of a split pied. Since a spangle budgie has only one spangle allele, the darker feathers could just be there because your budgie is technically split for normal (since spangle is dominant to normal striping, and your budgie isn't a double factor spangle). But I don't know for sure as I have never seen something like this. I hope I helped, good luck!