Mamiya 200mm F2.8 Problem, need other user's help

I just purchased a mint 200mm F2.8 APO lens for the Mamiya 645 body.

Its in perfect cosmetic condition. Today I ran my first roll of test

film through it and noticed one thing. When the lens is mounted on

the 645 body it sags ever so slightly. The very tip of the lens sags

a tiny tiny (tiny!) amount. Its probably just normal tolerences. The

side affect of this sag is that it does change the stiffness of the

focusing ring. Its nothing terrible but there is a noticable change

in focusing effort. Is this normal? This lens does seem to have some

very heavy elements at the front which would cause it to be so front

heavy, I'm just concerned about the focus ring change once lens is

supported by the lens mount alone. Any thoughts would be appreciated

from current owners of this lens. Thanks!!