transmission gurus

02 camaro z28. It seems like the shift points change after driving on the highway for a period of time longer than 15 minutes or so. You can start the car and take off under low load conditions and normally it will shift under 2000rpm. After driving on the highway for a while and getting back into city traffic it will start to climb to around 3000rpm before shifting still under low load conditions. Sometimes it seems to stay around 2800-3000rpm for a while while I let my foot off the gas to make it shift. It never slips and shifts fine at all times under hard acceleration. If you shut it off and restart it, it goes back to normal. This is a car that has been in a front end collision, not a bad one, and has been repaired. I think it has been sitting for a long time before I bought it and fixed it.
Thanks
Andy

Check the fluid level first. The computer "learns" based on your driving style but it shouldn't be learning that fast or that often... more like a lifetime learning.