I purchase a D90 in November, which I do love. However, a couple of days ago the pictures I have taken in two different basketball gyms have had problems. the exposure seems to look different on different areas of the photo. (Like from a pickish cast to a greenish cast) It seems to go from bottom to top or top to bottom, even a strip in the middle of the pictures. I have taken pictures in these gyms before and they were fine. The lens is the Nikon 70-200 2.8. I put the lens on a different Camera and the pictures were fine. WB was set to floresant. I stepped outside changed settings for outdoor and the pictures were fine again. Any ideas?