Subject: Precision of the moon's synchronous rotation

How precise is the moon's synchronous rotation? Is there any variance, even to 
the smallest degree? 
Over the period of millions or billions of years, should the syncronization of 
rotation and revolution differ by the slightest amount, we (mankind) would 
eventually see rotational views of the moon. This would eventually expose all 
of the moon's surface to the earth.

Re: Precision of the moon's synchronous rotation