I searched and found nothing. I am a new Subaru owner, (`87 RX) but with past other make cars, I've had this problem and it was the voltage regulator.
Periodically, and mostly at night, with more electrical items running, all of the idiot lights glow very slightly and then go out. There is no change in the volt gauge, at least not detectible. I'll just be stopped and the lights will glow a little, and then go out. It also happens when driving.
I am not real familiar with my Subaru yet, but could it be the voltage regulator?