Just ran across this blog post of a meeting at photokina with Michael Wollburg (Manager Customer Support Nikon GmbH) and a Nikon technician - guess there won't be anything official coming from Nikon: http://falklumo.blogspot.de/2012/09/photokina-2012-nikon-talks-about-d800s.html The root cause is a misalignment of the AF module when mounted, outside of Nikon's own production tolerances. ... It has been eliminated in the current production. ... The fixing procedure for Nikon is a tedious one. It includes writing individual calibration values into the firmware. For larger deviations, the AF module will first mechanically be re-aligned. This may actually include the AF auxiliary mirror in some cases.