I've had the fish 8 months. Its been in that tank for probably half that time. I don't consider it a new fish.
Also I think the tank size (58 gallon) is totally adequate for a dwarf angel, unless it is one of the largest ones.
The tang is a temporary resident, it was given to me for free because a friend was having some trouble with QT. The tang was quarantined and is going to a LFS soon.
He wasn't out when the lights came back on, but I remember someone posting a video of their Chaetodon larvatus doing the same thing. The reason it stuck out in my mind was because the fish was so hard to keep and there it was in the video doing laps around the powerhead. (I think he had a vortech as well, but can't recall for sure)