Brake light always on

I've had my '82 GL 500 for a few years and have done quite a bit of work on it, but not much electrical. I've been riding quite a bit lately, and just noticed yesterday that my brake lights are staying on all the time. The brakes seem to be working fine, although I do need to deal with a bit of a dragging front brake. That wouldn't affect the brake light, wold it? Is there a switch stuck somewhere? Any ideas on where to start? I appreciate any help you can give.Thanks!