Hmm, ok, I unchecked "disable device sleep while playing", so I'll see if that makes a difference. I'm not entirely confident, because it sometimes shuts the music off and sometimes not - the seeming randomness of it disheartens me.
I'm on Juicy's ROM, still 3.7.1, I think. Also interesting to note, I
sometimes cannot use Juicy's "long hold End key" to lock the screen when PocketMusic is playing. Sometimes it works though.