are these flashes coming from trucks behind you? or from oncoming traffic? sometimes when other drivers hit a bump it causes the beam to go up and back down, perhaps it could be the light under the cutoff that you're temporarily seeing that might look like flashes, unless you're certain that these drivers are flashing their highs at you.

 

I know when someone is flashing their highs at me man....they're doing it from oncoming traffic. How the hell would my lights be reaching them if they're sitting so high!? I don't get it