I'm glad I decided to send my Z8 in for service when I did, even though I wasn't experiencing any issues with mounting/unmounting my lenses. I thought it would prudent to error on the side of caution regarding this matter, rather than take my chances that something might go horribly wrong sometime in the future. So I decided it was better to bite the bullet now, rather than wait any longer and take my chances that I "could have" a faulty bayonet mount on my camera.
Now I am starting see a few posts with users saying they are now experiencing issues with their lens mount, when they had not had any problems before.
I know there is never a good time to send your camera in for service, but once this problem has been dealt with, it's nice to be able to move on and have some peace of mind.