I had a similar problem. It has something to do with the throttle sensor. As the sensor becomes worse the accelerator will become useless. You might have already experienced some problems with the accelerator...maybe not being able to rev past 3000 rpms..etc?
I was in your position with the light turning on after some driving and not being after restarting the car. After about 2-3 months of this behavior it was on all the time.
The bottom line: You will eventually have to get this replaced. Go ahead and do it now.
