I have had my NN3 for about a year now, and have noticed a worsening problem with leveling. I mount my camera/lens combo (Nikon D200/Sigma 12-24mm) and level as I always have, but now, the resulting image is crooked. I'm attaching a sample image, photographed with the level on both the tripod legs and the NN3 built-in level spot on. What could be causing this and how can it be fixed? It has gotten worse over time and now Panorama Factory is starting to have stitching issues that it's not had before. Any help is greatly appreciated!