If this is a fairly new helicopter, it my just be getting broken in. The more freely the flybar works, the more of the pendulum effect you will see. The bad news is that it's entirely normal for the CX2 to do this. The good news is that we have all been through it and there are ways around it - from mild to wild.
I'm sure that this post will bring The Collective out to play and advise all sorts of after market goodies. That's what we do and we thoroughly enjoy it.
To get you started with these little helicopters, this link may make a good read. It will get your heli set up well and give you a better understanding of how it all works. Then talk with the forum members and enjoy!
[link=http://www.heli-wiki.com/mediawiki/index.php/HOWTO_Wiki_Overall_CX_and_CX2_Setup]Heli Setup[/link]