Saw someone I know today but I couldn't remember who they are. It's driving me crazy

I was biking to Walmart and then I saw someone that I thought I knew. But I couldn't remember where from. And then they looked at me like they were trying to remember too, and then waved frantically at me. But they were in a car and it was at an intersection so they sped off when the light changed (they were going in the opposite direction as me). So like, I'm SURE we know each other. But I have no idea from where. It's insane. I can't remember if I know them from

-class/research group(probably not, because I would recognize them if I met them so recently)

-any of the sports I play (no! I've looked up everyone I know and can't find his face)

-my childhood (maybe??? But I grew up in Texas and I'm in CA now. Not very likely but still a possibility)

-SW/EP/Vent or any other online place - also possible, but I doubt it. I can't remember their name.

This is so insane to me because his name is at the tip of my tongue but I just can't remember. Oh well.