That is funny how it's on the one side. That reminds me of a horse my BO used to have. She was a gray arabian...or she was supposed to be.
There was a bush out in the pasture that she would stand over and scratch her belly on and her whole underside would be green!! And of course she was varying shades of brown and yellow every where else.. When I went on my horse search I tried to avoid light colors. I believe I actually said this once when looking at a gray horse that I almost bought, "but I don't want a green horse!!"
By the way, I think her tail is adorable at that length!