Insiders are blaming Paul McCartney's vanity for only allowing one-track to the charity collection, 12-12-12: The Concert For Sandy Relief. McCartney -- who according to our sources would only perform if he was the closing act of the night -- played one of the longest sets of the night, performing an eight-song set, including a new song, "Cut Me Some Slack" with the surviving members of Nirvana.

Despite the high profile spot, McCartney only allowed his performance of the Beatles' 1968 "White Album" classic "Helter Skelter" to be included in both the digital and CD versions of the charity compilation. A source told The New York Daily News: "Egos are also to blame for there only being one Paul track. He didn't like the way he sounded and would only approve the one on the album. A shame, because 'Blackbird' was so beautiful live! It's unfortunate that celebrity ego can tarnish even a concert for charity."

SIDE NOTES The Rolling Stones' Ron Wood revealed to Hello! that in addition to Rod Stewart, Paul McCartney also served as best man at his December 21st wedding to Sally Humphreys. Wood said that McCartney first showed his approval for Humphreys during his own 2011 wedding to third wife, Nancy Shevell: "Paul was saying at the time, 'Wow, this is wonderful, you two make a great couple.'" CHECK IT OUT: McCartney's performance of "Blackbird" at MSG during 12-12-12: The Concert For Sandy Relief: