Well I'd assume that it is unrelated to your E-test. Sounds more like a faulty sensor to me. The ABS/TC are closely related at least on earlier models as the TC uses the brakes to assist its function. As you've said it clears up after the car is restarted. If you have a MTX maybe tyr this. While there is no one around on say a long down hill put the car in nuetral when it exhibits its symptoms. Turn the car off and coast for a minute and then restart the car. If the light goes away then it really does sound like a sensor to me. If it is still there it is more probable that it is mechanical perhaps going away when something resaets itself in park. As well if you haven't already done so you may wish to post in the Troubleshooting section.
