Black hairs on westie?!? Questions

Hi.
I have a gorgeous 7 month old westie who has suddenly developed thick black hairs down his back. Skin is lovely and pink and my groomer says this is not a skin condition as its just the hair not the skin that's changed. He also has very floppy ears that only come up occasionally. I understand that to give this time as he may still be teething but I'm wondering if there's a gene deficiency somewhere or if this is normal? He was purchased from KC registered breeder and I have full pedigree cert so am very confused. Has anyone come across this or has any advise?
Thanks in advance ☺

Maybe a fellow Westie owner will join this thread, but I've never heard of this problem. We have been asked about black skin but not black hairs - do you have a photo? If these are just the occasional black hair I'm wondering whether most owners would just pluck them out - I suppose that would depend on how widespread they were.
As the puppy's breeder is registered with the KC, (I'm not sure whether you mean a KC Assured breeder, or just that they have a registered affix), I would be inclined to ask them about the black hairs. A breeder should be prepared to give advice for the lifetime of the pet.There's not much to be done about the soft ears I'm afraid. I hope they do come up, but they really should be standing by now. I am sure that you love him just as much, however his ears are.

Hello. Thank you so much for coming back to me. Yes we love him regardless, he is a bundle of joy. We were just a little concerned by his differences.
He has large patches of black hair so we couldn't pluck them out. I've heard of the dorstal stripe but his is definitely black not cream/beige. I have attached some pics of how his hair looks gathered and close up.
I'm just so confused as I met Mum and Dad and they were both 100% westie! Do you think this could be some rare gene throw back? I really appreciate you replying.

You might ask the breeder. It's possible it is a "genetic throwback".

Thank you I feel awful keep asking the breeder. I don't want to her to think I am complaining as I wouldn't change him for the world but just want to know he is healthy and not at risk of any illnesses!

A good breeder will be happy to answer yourconcerns.

I don't think that this is likely to be a sign of illness, far more likely to be a mismarking - but I don't know how common this is. As you probably know the Westie was originally a colour variant of the Cairn Terrier, purely selected for its white coat. I suspect that the black hairs may have something to do with these origins, but I have no insider knowledge.
You seem a very polite lady and if I was the breeder I might be interested to know about this unexpected marking on your boy. However, if you are reluctant to ask, I see that there are at least two Westie groups on Facebook - perhaps this might a good question to ask other owners.

Ah you are all so kind and helpful on here.
Yes I think i need to speak with breeder. I was wondering if maybe it was to do with his new big boy coat coming through and would possibly not come through as dark now. Thanks so much!