Riding into work this morning I was about to pass another rider (3 lane freeway - he's in the middle, I was in the outside) but I see his right indicator is on. Being a nice sort of guy I hang back and give him a nice big gap to move out into but he just carries on in his own lane. Later on down the road I see him again, still in the same lane and still with the right indicator going... I considered trying to tell him but a full face helmet and freeway speeds do not lend themselves to easy conversation and any other signals (eg. getting in front of him and flicking my own indicators on and off or something) would probably just cause confusion for him and other road users. So how would you do it - or do you just let him go on his merry way?