Do big lenses damage lens mounts?

I've wondered about this too. I rented a 70-200 VR2 and TC20III a couple weeks ago and I never let it hang from my neck. I always held the combo by the lens when walking around and such.

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Nikon D90, Nikon 17-55 F2.8, Nikon 18-105, Nikon 35mm F1.8 - Sony NX5U - Adobe CS5 Production Premium