Had something vaguely similar on the way to work years ago.  I was driving along the country lanes 60 speed limit when i catch up to some woman in a merc driving at 40.  I drive up and down these roads twice a day and it takes over an hour on a good day so there was no chance i was going to sit behind her so obviously overtook.  As I'm pulling infront (plenty of gap) she blasts her horn and flashes her lights, i thought plenty of gap heh... carried on. 
  
Then i come to a village, speed limit 30 and slow down.  About 1/2 to 3/4 way through this 30 zone a silver merc overtakes me as i was doing 30, i though what a **** and i notice it was the woman i overtook earlier.  Along comes a national zone again and she carries on at 40, I catch up and overtake.  Again horn and flashing lights and i'm thinking CRAZY but carry on.  Another 30 she overtakes me and when i catch up to her in a national section she's doing 40.  I'm thinking defiantly crazy at this point.  At the first opportunity overtook and same again (horn, lights). I made a rude gesture at this point and carried on.  Didn't see her again cause there were no more villages.   
  
Very very weird experience...