I'm not 100% sure, but I believe the small increases in rpm's is an electronic choke. It's totally different than older cars, and probably to complex for me to understand, but I think that's what it is.
Mine does it too, an '04 GTS with the electronic throttle. I've got less than 8K miles on the car. It could be a dirty MAF, but with this few miles, I'm having a hard time believing it. So, maybe its the electronic throttle.