It's a good point, Pete, but remember, even when I don't have my hand in contact with both the body and the lens barrel -- i.e., on the zoom ring -- autofocus occasionally locks up. Also, I can put my hand in the same position on the D800 with no problem. I do that routinely when I brace the camera on my left shoulder. Also, what I haven't mentioned is that I've had the D3 since January 2008, shortly after it came out. Never had a problem until last year.
In any case the D3 went winging its way back to Nikon this morning. Before I sent it off I had a fairly extended chat with one of the techs there, who entered notes on our discussion into the case file. I'm quite sure the camera will get a thorough examination this time.