I could see Mark flying all the way to LA just to do some harmonies because he's got the money and the time and because he probably really wants the EP to be the best it can but I want to believe it's for something more. Also, if its true, I like the fact that the christmas song isn't really a christmas song. I didn't preorder this but I will definitely be picking it up from iTunes when it gets released.
edit: here is the interview on soccer AM
http://www.youtube.com/watch?v=7kKhlGxJiVA