2 short honks and light flash meaning?

Posted by lemdrag@reddit | Truckers | View on Reddit | 13 comments

Passed a truck and they honked 2x and flashed their lights. I assume the flashing meant ok to get over.... Then they passed us and flashed lights again. what's it mean? I suppose we'll get off at the next exit and walk around to make sure the vehicle is ok, just in case.