I guess if you're having a concern I would bring it to the dealer's attention. Perhaps they missed a reset or something. However it seems unlikely that there is anything wrong with the car if the a/c is working and still getting as cold as before.
I know it takes a little bit of time to overcome the latent heat and the a/c to start feeling cold. It depends on how hot it is though, when its below 80 it cools off very quickly, if you purge the super heated air from inside the cabin for warm air from outside it cools quicker to ambient before pulling down to the desired temperature.