This is completely normal, there is always a self-defense reflex if you hit yourself, I had the opportunity to force a female to whip and cane herself, this was very quickly abandoned.............
No matter how you try, you can never really whip yourself hard enough for it to be truly effective. I've used canes, floggers, riding crops, switches and the cat o' nine tails, and ended up with a lovely red bottom, but without the searing pain I crave.