Themos

Hi everyone. I bought an A3 6 months ago and have 6,500 miles on it. For the last couple of months, I have been periodically driving on the S mode. I enjoyed it at first. However, for the last couple of weeks, I have found that there is a delay in upshifting from the 2nd to the 3rd gear. The RPMs approach the red zone (around 6,000) before it upshifts, and of course the car does not accelerate as fast as it should. I took it to the dealer - the technician said it was shifting fine. Has anyone experienced this probelems? Thanks