The title says it all. Maybe this is a stupid question, but I've been running for decades and I don't know the answer. As a driver, I've never flashed my high beams at a runner, so I have no idea what it means.
Are they acknowledging that they see me? (At night I usually run with a headlamp and a reflective hat and/or shirt.) If so, I appreciate the gesture, but it's usually just blinding and kind of annoying. Just this evening I had this happen. It wasn't just a momentary flash of the high beams, it was turn-on-the-highbeams-when-I'm-100-feet-away-and-keep-them-on-as-I drive-by.
Are they flipping me the bird via the headlights? I almost always run in the bike lane, against traffic. Except for blind corners I'll hop up on the sidewalk. And I have zero assumption that drivers see me. I never run in front of cars at a stoplight at night.
Consider me stumped...