I don't think it's moisture since I've had the AE's on for about 9 months now with no issues.. and more recently I've had them on for about 3-4 months since I last touched them in any way. It literally happened out of nowhere.
Also, I've had condensation before (enough to visibly see inside the housing) and while that has caused the headlight failure warning, they still turned on, I dried them out, and they worked great as ever since. This was on my old headlights before an accident, so it's not an issue of an old problem coming back, either. It does take a visibly apparent amount of moisture to affect the lights, since the lights are NOT vacuum sealed and there is inherent moisture in air anywhere.
This time, no condensation whatsoever, no touching the lights at all for months, no anything..
I guess take this as a warning if you mod your angels.. even if you do absolutely everything RIGHT, the headlight system seems to be able to crap out by itself anyway. And even though it's not your fault, BMW will try and say it is, as usual. I have heard of other people with completely stock lights who had the motors in the adaptive lights just go, and had them replaced under warranty..
I think I'm just gonna wait for a ridiculously dry day, take a hair drier, and dry the lights out extra (just to be sure), put everything stock and bring the car in. I think it's the motor that's the issue, since there's no way it can be moisture, unless a new hole or leak suddenly opened up somehow? I'll let people know how it goes, but this might not happen for a little while since it's been humid here. It's not a big problem since all the lights work perfectly fine.. that freakin' warning light is just annoying, I can never see what my cruise control is set to any more!