The brake warning light will come on if your system is low on fluid. It can also come on if the rubber gasket in the master cylinder cap has fallen down and it is hitting the sensor in the master cylinder. It also signals an imbalance in the system or if the combination valve is bad. there could also be a loose or broken park brake lamp switch on the parking brake assembly. You should also check your rear brake lights and see if they are working properly. Since you are talking brakes here and since they are a pretty important part of your vehicle, and everyone's safety, I'd suggest you get it at least scanned and see if you come up with an error code. Autozone and many other places offer this service for free. Have it looked at just to make sure you and others are safe. It could be a simple fix or as involved as your body control module. Hope this helps, good Luck.