Hm. Well, I guess that depends on your definition of endo. I don't think you could describe it as "simply a fall"... to me, a "fall" describes someone, for example, who didn't clip out early enough, and just fell over. Anyway, it happened so fast that I don't remember exactly how it happened, but I think when my front wheel started to skid, I flew forward (which still perplexes me, because my bike skidded to the right, and I fell to the right) and hit the dirt. Hence the face plant.