Aikido as well. I slipped getting out of the shower not too long ago and instinctively tucked my chin.
Another time more recently I was dashing up some concrete steps with a DSLR in my hands in front of me. My toe caught a step just as I hit the landing. I was headed towards a face first fall with the DSLR between me and the concrete. Instead I instinctively turned, rolled onto my back, and sprang back to my feet.
I had a similar experience when I was taking Aikido classes, dropped my motorcycle, (high-sided over the tank/bars) and instinctively tucked my head and rolled. I had a backpack on with schoolbooks in it and rolled back up to my feet, suffering nothing more than some mild bruises.
Another time more recently I was dashing up some concrete steps with a DSLR in my hands in front of me. My toe caught a step just as I hit the landing. I was headed towards a face first fall with the DSLR between me and the concrete. Instead I instinctively turned, rolled onto my back, and sprang back to my feet.