That is about what mine runs with the outside temp. aroud 85 - 88 degrees. When you begin to push it a little things go up about 10 degrees. Like all of the current "V" owners I am waiting for the oil temp fix from Cady. I do not think that the oil temp is really that much higher than the water.
I have seen water temps from 195-215 (in my CTS-V - seems normal). From my experience in other cars (non LS6) oil temps are 30-40 deg over water. So in *MY* opinoin oil should only very rarely (hard/track use) get over 260.