So I have this eight year old chestnut mare named Summer [aka Summer Breeze] and last year I noticed a few hairs on the left side of her nack turning grey in just a few places which looked like roaning. Yesterday I did a full-body grooming and noticed there are more, that stretch about 1/4-1/2 the way up her neck. She's also starting to get a couple of gray parts, some that are just a couple strands, some that look like grey highlights. Do you think it is just because of age, or maybe breed?