Chuck,
I have this (not illuminate) happen about every three/four months, I took to dealer one time but got "not able to reproduce bring it in when it happens again" . I had it happen again but by the time I could take it to dealer, like you it had started working again so didn't bother.
It seems BMW dealers these days can diagnose problems only when they are occurring, have to wonder what good all the electronics is. I have read about this problem regularly so I think there is a defect and BMW just doesn't want to recall to replace the system.
What do you do to reset ?, I usually turn off/start car (sometimes several times) until it comes on.
Compared to Japanese cars BMW is in the dark ages on electronics, my daughter can talk to her Acura and get all kinds of info, I can't even get my X6 to understand a number from my phonebook it uploads to dial it (I miss the system my X5 had where I could enter names and numbers myself).
If you do go to dealer let us know how it goes.
