I always had this doubt myself. I used to write loooads of song lyrics into my scripts. Still didn't research it enough, so still no clear answer here.
That said, Ales Kot, a writer for many comics at Image, writes a lot of movie and song lyrics quotes into his books, and they're published/sold. I guess if we're not even profiting out of it, we should be ok too.
(Take my opinion with a grain of salt, though)