There is a powering down sound that comes with them staying on, as soon as it stops, you will notice the AE's shutting off as well. No one really know's what the sound is. It sounds like a small electrical motor shutting down (like a buzzing sound). The Angel eyes are fine, don't worry about it. That is normal after shutdown, mine also does the same. Also, most of the time it does shut down within 10 seconds, but periodically it takes a few minutes for me too. It will shut off eventually.
I washed my car one day, (I have the exact same CCFL's from Mycarr) and got one of the black inverters wet, it fried itself as soon as i turned the ignition over, so only one side works now, just a warning to make sure you hide them really well or water seal them. If you know where to get a new black inverter, let me know.
330i | M Technik | BBS 197 | 3D Studie | H&R