93 dash brake lite

My dash brake lite came on and stays on. At the time my brakes felt fine, no problems. Well after 2 days, I notice as I come to a stop, the pedal will fade but does not go all the way to the floor. I checked the fluid level and all was good. Would the brake booster cause dash lite to come? Or does this sound like more of a master cylinder problem? OR am I looking in the wrong area.

Thanks for your help