A little movement is OK. There is a spring washer that allows this.
Use it until something else goes wrong. Then have it serviced and this checked out as well.
In Malaysia, its around 600USD for a CLA incl. shipping to Solms.
Been happily shooting with a M6 for the past few years, latest photo taken with it : http://2.bp.blogspot.com/-ewX4O_34SJA/T4g2JpFlYuI/AAAAAAAAAHs/iihS4xBhK2o/s640/photo+(11).JPG
It is tight...
Also noticed that the shutter release on my MP feels a bit ummm... different when compared to my M6. MP release feels a bit like those on M7s.
Requires a wee bit of force, M6 smooth all the way.
The MP wasnt used much by the previous owner. And i just shota roll since purchase last week. Guess it just needs some exercising!