I noticed this too. However, I've only fallen once and it was bareback on a fat horse.. She took off, so I tried grabbing more of her neck instead of the reins because when she tried getting too fast, she'd slow down. Well, she didn't that time and I slid off with my arms wrapped around her neck. I was loped over. I agree with PaintHorse. The mare just stopped and when I opened my eyes, I was under her belly and she looked down like "what are you doing?"
I dunno. Now I wonder what I'd do if I fell again..