There are several reasons why this could have happened. First, it needs to established if it is always on or does it turn off when you turn the engine off? If it goes on and off it could mean that a sensor is faulty, which isn't a major problem.
However to be on the safe side, you can always call our 24/7 Roadside Assistance via the free number and have it checked out. Then they can see if they can get you in somewhere to get it scanned and hopefully sorted.