[yobiebs]

I posted about this same issue the other day, and got a great response from Cal Cruzer:

Your brakes are wearing and more fluid is now in the hydraulic system lowering the level in the reservoir.When you accelerate the fluid level drops enough to activate the sensor. Although the light comes on when you activate the emergency brake, it is also w low fluid light. You can add some more fluid to the reaservoir and it will stop or you can do brakes and it will stop. Your brakes probably have more wear remaining on them but if you add fluid be sure to take it back out before you compress the caliper pistons (or brake cylinder pistons depending on your model) when you do brakes or it will back up out of the top of the reservoir and make a mess.

good luck