They lighten up all over their bodies as they grow. If you look up pictures of Finkies, you might see some of the older puppies/dogs with some black still on the tips of their tails. This is pretty normal up through the age of 4-5 or so, but depends on the dog. Bubbles has no black on her tail, but Kimma still does have a bit, though they are only 2 weeks apart in age. Even though these two are young, I've already noticed them getting lighter