Missing Songs?

Hi tapulous, as soon as Tap Tap revenge 2 came out I downloaded all the songs, but just recently I went on online mode and saw the song "Better days" (which is one of my favorite songs) and it was downloading so I was confused and thought maybe I didn't download it. So I checked the "Downloads" section and it wasn't there. Then I went to "DX-Chain's room" and there was another song that was downloading so I checked the "Downloads" section but it wasn't there. So Do I have to delete a song or is there a limit to how much you can download or is this a server bug?