Not only did I fall, I fell hard.
I had put the cleats on my shoes, and in fear of overtightening them,
undertightened them.
It was my bad luck to want to unclip at the top of a short little 15% hill in my neighborhood. So instead of just falling, I went backwards first, steered the front wheel over to the right, and fell down to my left, getting body slammed to the asphalt.
Ugh. That hurt. And had to take the shoes off to get up.
You can bet I've never made the same mistake again.