Many of us battle this vary issue..
 

When I first bought my car this light was on, replaced the pads, still on, cut the wires and the soldered the ends. The light will go off for a week, on for a week, it has a life of it's own. Someday I'll track this down and find break in the circuit. Good luck, and I hope it's the pads, the warning light does come on way early, when you still have plenty of pad left.