I would have never have thought of that as a flat back. I guess I'm used to looking at my old chunk of a QH.
Just took a relook at my pictures. The mare was unusually fidgety and really not paying attention to me. Couldn't figure what her problem was but in the first pic just above the wagon I have my answer. The bear. The ground dips down in sort of a drainage swale there so you only see his top half. Blackberries are ripe. Yum!