Red sex-link pullet with ONE black tail feather??

I hope I'm putting this in an appropriate section of the forum......couldn't really figure out where it belonged

I've got 12 red pullets from the TSC "Assorted Pullet" bin....so I'm not really sure if they're RIR, or just some variety of commercial egglaying red sex link, or some of both....

Anyhow, went out to feed them today & noticed one of them has a single, BLACK tail feather. I had to catch her just to get a closer look at it...it's buried amongst her light/whitish tail & rump feathers and it looked like a big clod of dark muddy dirt at first. But no...it's actually a black feather. Looks like someone dipped a bit of her tail in ink!

I'll get pics later if anyone is interested. For now I'm just curious if anyone else has seen this sort of thing in a red hen??

I was wishing I had a good way to tell them all apart so I could name them. I'm thinking of tying colored bits of string around their legs so I know who's who. She came up with her own solution- she must REALLY want to prove her uniqueness....so she is the first red girl in the coop to get the honor of a name. I have dubbed her "Inky". Ought to confuse my guests who aren't looking very closely when I introduce one of my red hens as "Inky"....LOL. Now I should name one of my little black ones Ginger or something, LOL....

I have 3 Red Stars. One has a single feather in her tail that's not completely black, but is half-black. One has a couple of feathers that have a thin line of black at the edge. So it's probably pretty common.

I got my girl Ophelia from TSC as a Golden Comet. She basically looks like all other red sex-link pullets. She is my friendliest bird and today while she was sitting on my lap, I noticed that her white tail feathers have black speckles on them. I found it funny.

sexlinks are hybrids, technically MUTTS.....I think anything is possible (within reason)

I have a 6 week old chick that has a couple black tail fewthers. We thought it was a bug at first so we named her Cricket