I observed this with Google Music too. Nirvana is underrepresented in my music collection (1-2% tops) but I seem to hear multiple Nirvana songs every time I log

I observed this with Google Music too. Nirvana is underrepresented in my music collection (1-2% tops) but I seem to hear multiple Nirvana songs every time I log in and shuffle all (4-6 hour period). I have wondered if Google Music is picking music that is related to previously heard music. But I have no way to check without looking at the source. Until Google Music gets smart playlists, I have no recourse I guess.