http://gothamist.com/2014/02/07/phish_mike_gordon_cactus.php

So there was this rumor going around that the reason why no covers were played during the four night run was because of something Billy Joel said, because he was supposedly upset he couldn't play the Garden on New Year's because Phish keeps booking it. And the rumor was that he said, 'Phish is just a second rate cover band.' The flames of this rumor were fanned by a Tom Marshall tweet. Really? I met Billy Joel once and he was really nice, but I haven't heard anything about that. I know he was playing a lot at the Garden but I didn't know he was looking for those dates.

mike gordon interview