I have heard this from other people. Could you tell me a specific place in the game where a song not in the USF set plays? Preferably, could you make a save state just before that point so I can see what happens when that song is loaded?
http://www.savefile.com/files/8044082 here is batch one. Each .zip/.pj file is a different state. Most of them are right before the music changes, so all you have to do is go through a door or watch a cinema thing.