As a professional driver I know perfectly well what flashing lights mean. and the highway code,.
If anyone has noticed when passing the 20mph flashing amber warnings outside the schools,as you get nearer to them they can appear to go out .
A similar thing happens to "some" cars with led lights and could be confusing with one thinking that a driver is flashing at them when in fact they are not.but just going over an uneven piece of road.
Its all to do with the width of the beam I think.
Possibly i am the only one who has noticed this,but I doubt it.
With many motorists being friendly and giving a flick of the lights it would be easy as I nearly did and innocently pull out thinking they are giving way to you..