Llights come on???

Well, as I mentioned a couple of months ago.... the ex has this '87 535iS that I was going to get. We still haven't gotten around to making the deal, but she took it out today---first time it's really been driven in a few months. Everything seems fine, except... for some reason, the headlights come on by themselves, go off, come on. Kinda curious, it would seem to me. None of the warning lights are doing anything, except the brake one which has always been on. Any ideas on what would cause this, other than possession or gremlins or something like that?

Short in the wiring? Headlight switch disintegrating internally? I recall hearing someone else had a similar problem and the switch was faulty.