Could be a funky headlight. I've got one on my van right now. Goes well with the dashboard lights that come on sometimes when I give the dashboard a little english. But I'd also check the condition of the terminals on the bulb and its' connector. They could probably stand a sand and lube (dielectric paste) anyway. While you're at it you could check for power at the connector on hi & lo. And a +1 on the switch and its' spring-loaded contents.
All of the above are going to have to be done sooner or later.