I've heard of something like this before although I'm not really sure why it happens. I've heard that as some cockers get older, their coats can change color but I've not heard of their paws changing color.
I've also heard of noses turning from black to brown or brown and pink. I think it's called snow nose, but I'm not certain.
I, too, would be very interested to hear what others have experienced and if anyone can shed any light on the subject.