Probably a bug with this map: The volume of the music which played at the beginning of this game was set by the "sound" slider, not the "music" slider.

Okay, let me rephrase. I have my music slider zeroed out, and I don't hear music on any other map. I did hear music on this map.

EDIT: I can't recreate the problem now, though. The music was unfamiliar to me; is there some "space music" especially for asteroid maps?

So to sum things out:
Aquanim heard music while playing on this map but it was music that was not from ZK.
Conslusion: Either you are going insane, some neighbor just started playing some music and you didnt notice it, or you had web browser opened and some ad started to randomly play.
Oh nevermind there is innate music on this map :P A good enough reason to unfeature it as there might be copyright problems.

quote: (music shipped with map is treated as "sound")

Okay, mystery solved.

It would be a shame to unfeature this map for that. I'm not positive the map is positionally balanced (it's definitely asymmetric) but it is interesting.

Wat? Unfeature yourself Orfelius!
Music AFAIK has a "libre" license. I've got to back home to find it out.