Good to know you're OK!
My first (as an adult) was more embarassing. I decided to run an errand to the hardware store. I got there and fell over trying to stop in the parking lot. It turned out that a clip-on cleat had worked loose and I couldn't get out of the pedal. I had to add bandages to my shopping list!
I also wondered why I always rode like a drunk. After years of maintenance, I discovered that my rear wheel was true, but not properly dished. The rim was about 1/4" off center, and I kept riding off the shoulder. I spent an afternoon dishing the wheel, and suddently I could ride a straight line! That problem caused a lot of minor accidents.