You are very lucky... Mine had that problem too and had the shutter replaced by nikon india @ bangalore. I had some spots reappear after 2000 or so clicks and when I took it back to them they just cleaned the sensor and gave it back. I will have to wait to see if mine picks up dust and oil again.
- Radha D600, 50mm f/1.8D, 85mm f/1.4D, AF-S 105mm f/2.8G ED IF VR, AF-S 300mm f/4 with Kirk Lens Collar 18-35mm f/3.5-4.5D ED IF, AF-S 70-200mm f/2.8G ED IF VR II with Kirk Replacement foot TC14EII, TC17EII, TC20EIII