let me ask you first have you had brakes worked on recently? if not check fluid in master cyl and if low add some see if it go's out. if it goes out i'd pull rear wheel's see if wheel cyl is leaking if you don't have rear dist on it. but if light go's out your master cyl could be leaking. so keep a eye on it for a couple 3 day's if you have to add. another thing is e-brake might be stuck on a little......good luck......