How smooth is your OMD mount?
Like you, I was surprised on how tight the lens mount was when I first got my camera (coming from an E-510), but I notice now that -in my case at least- the tight mounts are the weather sealed mounts (the kit zoom and the MMF-3 adapter), with the friction probably coming from the sealing ring around the outside diameter of the mount. A non-sealed aftermarket adapter with a metal mount goes on much more like the 510, and the plastic-mounted 40-150 zoom glides on like it was greased.
(Of course, that tightness from the o-ring seal on the weatherproof mounts is also a reminder that with time, o-rings either wear down or are broken down - so those mounts probably won't be quite as weatherproof as the years go by.)
Interesting. It's definitely tighter with my 60mm macro, which is sealed. But it's still pretty tight with the 45mm, which isn't sealed.
At least I'm not alone on this one.