Phantom + A90 question

How ahve users of this combination dealt with the inability of the Graham headshell to touch all three contact points on top of the A90? I'm considering the use of a carbon fiber shim from Millennium, pre-drilled with holes for the cartridge screws, between the cartridge and headshell to provide full contact. Think it's needed? Any other solutions? Is it even a problem?

Thanks,
Bill