The subject may have been static, but you could have been moving, even slightly. As JRP says, the high resolution of the D800 makes any camera movement more apparent in the image.
Just for an experiment, take a lens in the 50-100mm (no VR) range, shoot in light bright enough so you can shoot at f/5.6 to 11, a shutter speed of at least 1/500sec and ISO 100-800. See if you images look sharp.
If so, then back down the SS until you start seeing blur.