What did your API provide ( downloads or just search?)
From someone elses comment, looked at the google cache of your github repo,
> groovr.getSongFile songs[0].SongID, (err, file) ->
might have been the part they have a problem with?
It provides only basic search functions of course, but it is publicly documented and I'm sure Grooveshark can't complain if you use it. I wrote a Go package for it years ago (literally, 2010 I think) and it still works fine. You get tinysong.com shortlinks, which lead to the song on Grooveshark.