2SSRSCAMARO

This Girl needs some advice. Just had the exhaust upgrade installed by chevy dealership on my 2010 2SS/RS L99. I noticed right away, while in automatic, if there is any acceleration while at a constant speed there is a quick and sudden rpm increase from say 1100 to 1300 rpm for a burst and then back down to 1100. There is no surge and no shifting problems. It is more evident in the sound since the exhaust is a little lower in tone and louder. (Sounds awesome!) It does not happen in Manual using the Tap Shifters. So, here are my questions. Was this always there and I just notice it now due to the louder exhaust? Is it the 4 to 8 cyl kicking in and out? Can I get that tuned out? I am going mad. I have always listened to my engine while driving and I can't get over this. Anyone?