i suggest you put some hairspay on some cotton wool and give it a good rub. In future, when you rinse your hair dye off , just put a little water on the hairline and rub colour on colour.This gets the majority of it off. I do it for a living. Try the hairspray though!
if you have access to any cigarette ash, my hairdresser always says this works worked in on a damp piece of cotton wool, although as a non smoker, I've never tried it out.
I dye my grans hair regularly (black) and she used to have black ears and black forehead and back of the neck until I thought of putting baby oil on the areas before I dye her hair or anything I have thats a bit greasy.
Once the hair dye gets on the greasy skin its easier to wipe off
Next time smear Vaseline on your forehead,ears back of neck purelizard. Its a great barrier:-) Bobtheturkey,cant you give a sensible reply to anyone? Grow up!