Nikon Rumors:

Nikon published a new technical service advisory where they announced a free cleaning and free shutter replacement for all D600 owners, even those with expired warranty. You can send your camera even if you do not have a problem.

If you have an affected D600, go to the Nikon site and schedule your free service. If your D600 isn’t exhibiting any of the (sadly common) dust/oil issues (mine isn’t), hold off on scheduling the service until the first mad rush is over but make sure you definitely do it some time in the next three to six months.