Hey, I own a B7 Audi A4 2.0T

Does anyone experience low rpm power fluctuations when running the premium fuel from Centex?

I don't appear to notice it when filling up with Shell...

To go into detail, I find when I'm running at low speeds and my rpm is under 2000, i notice the rpm needle and speed fluctuating a bit while I'm maintaining a steady pressure on the gas..

SHould I be concerned? Am I misdiagnosing the problem??

Thanks,

Ray