I have a similar issue with the brake warning light coming on and IT IS NOT the fluid level in the master cyc. Here is the related link
Was Solution Ever Found to the Issue of the Emergency Brake Light Randomly Coming On?. The problem is still unresolved. It's going back in the shop for the 9th time for another new component. I will post an update. At the very least, you should see if there if the vehicle is shooting any codes. Mine has posted several.
Good luck.