I woke up in the middle of the night and my room was lit up by that message on the phone. I thought it was because I had downloaded a battery monitor application. I didn't hear a "beep", but the ring volume was set to 0 and I was asleep.
I'm trying to get the phone back to 100% again, but it seems that it must take several hours of being plugged in continuously to trickle all the way up; it still hasn't reached 100%, today.
This issue makes keeping the phone on the nightstand impractical, as it's simply too bright when that notification is on screen. (If the notification can't be disabled or rooted away, I'll be returning the two "media" docks that I purchased on launch day since I have no other use for them.)