'Zero-speed falls' are a right of passage that every clipless user experiences at least once. It happened to me just the other day, embarrassingly while I was teaching a friend how to track stand.Of course, it was down to a rock getting stuck in there (I was on the mtb), but hey ho...
Anyhoo...I'm wondering if maybe you haven't figured out which is your 'chocolate foot' yet? This is the foot that your body naturally gravitates to while you are riding. An easy way to tell is to see which foot is forward when you are going down hills and out of the saddle. It will feel more natural to have one foot forward vs. the other. This is usually the same foot that comes out of your pedal at a stop.
Perhaps your left foot is your chocolate foot. It doesn't matter if you are right or left handed, this doesn't determine which foot is dominant. I'm right handed, and my left foot is the one that's out of the pedal when I stop.