Couple of my observations at my last couple fill ups. Fill ups are a 7-10 days apart and I always let it fill up till is stops on its own, do not add any more gas. Also always move the nozzle in and out of the filler neck 2-3 times.
Fill up A: I started the car and let it idle on its own.....rpms dropped to 500 and jumped back up. Sat there for a few minutes and it dipped again but not as low as the first time.
Fill up B: I started the car and held the rpms to 1200 or so.....rpms dropped. Let it idle on its own and it dropped again.
Fill up C(last night): I decided once the tank filled up that I would let the nozzle go in and out of the filler neck a couple times and held the nozzle partly in the filler neck. Turned on the car and let it idle on its own. Rpms dropped but not as bad at the prev 2 times.
During normal driving, in between fill ups, the rpms will drop when sitting at a red light but doesn't happen all the time and doesn't seem to happen at all after going below half a tank.
Its becoming an annoyance so I might try to video it or go to the dealer when I am close to needing gas and drive the tech half a block away to the gas station I regularly use.