I appreciate the quick reponses.

I checked the brake fluid level, and it is at the max. I had it drained and refilled back in the spring, and I don't think it is the brakes. I think it is more electrical. Also, the "brake lamp" indicator light is on, not the brake light. This light is below the light that shows if the trunk is open. I checked again tonight, and all the brake lights work fine unless it is warning me one of them is about to burn out.