I have no personal experience of this, but it's interesting to see the different takes on this
http://www.dslrbodies.com/newsviews/nikons-d750-rock-and-hard.htmlBoth D750 problems fall into those issues that you really struggle to deal with as a manufacturer.
Yes, the defects are almost certainly there. But how many people will actually encounter them?
So here’s Nikon’s dilemma: out of tens of thousands of users, maybe hundreds have encountered the issues.
Probably less given how few examples you see posted.