Is this rabicano?

I’ve noticed a lot of white coming out in our 11 year old sport-bred QH mare, especially at the tail, flank and mane. She’s always had random white hairs, but it seems more noticeable this year, or maybe I’ve just now started to really notice it. Is this rabicano? If so, what causes it?

Maybe, but more likely random white hairs from Sabino or some other unknown white pattern. Rabicano tends to be there all the time, maybe seasonal, but unlikely to start appearing at 11