Kimberly, go ahead and change the transmission fluid. Chances are the gasket that is on there is still good, but you will have to inspect it to make sure.
Regal Guy, you are confusing transmission flush with a pan drop fluid change. A transmission flush can remove deposits that might be masking an issue, and there is a lot of discussion on whether to do that on older transmissions. Personally, I feel any transmission issues that arise as a result of a system flush were going to pop their heads up in the near future anyway.
On the other hand, doing a pan-drop fluid and filter change does not create the issues a flush might create.
2001 Bonneville SSEi (retired at 365,000 Kms.)
2014 Jeep Grand Cherokee Overland (yes, I know its not a GM)