Toyota Repair: 00 Camry brake light cold weather, emergency brakes, electrical problem

Question
Whenever the temperature drops into the 40's or lower my emergency brake indicator light comes one.  It doesn't stay on all the time, but will come on for a few minutes (or seconds), go off, back on, with no particular pattern.  The emergency brakes are not engaged, and work just fine when I pull the handle.  Engaging the brakes makes the light come on, but releasing them won't neccessarily make it go off.  This seems more like a switch or electrical problem than a mechanical one.  The only maintenance done on the car recently has been routine oil and filter, rotate and balance.  Any ideas?

Answer
Open the hood and check the brake fluid in the master cylinder reservoir it is probably low, adding brake fluid will make the warning light go out but you need to have the brakes checked as low brake fluid level also indicates that the front brake pads may be worn and need to be replaced.