Similar thing once happened to me - many years ago. I got bounced off over the first fence of a coffin. Horse kept going, circled round back to me. I climbed back on and re-did the jump. When the scores came out, I had no stop, just a fall???? TD said they had all talked about it, but horse never stopped - I just fell off. He also said that they did discuss what they would have done if I hadn't re-taken the fence, since they had already decided that the horse hadn't stopped!!!