Sounds like valve is stuck. What You're gonna wanna do is hook up the sds and verify, drop the gas tank, go into parts, get the valve, replace it and then lift the assembly back into place.
Tell the dealership. Maybe even have a shop foreman ride with you to fill a few gallons. don't fill it up so you have space to fill it to verify remedy.
I'm more prone to the first one, but then again, I've been told I get paid to work on my own ****. Also, have you tried not sticking the nozzle in as far?
My new postal Metris van has developed this problem, slow fueling, after around 12 fuel ups, 2500 miles of dusty Kansas roads (rural route). I can see the fuel backing up in the fuel tube after the fuel nozzle kicks off at only few gallons filled...and then it will fill with 10 more gallons, with me slowly adding more gas. I am wondering if dust built up on a vent. No other issue.
edit, next fill up went well for 5 gallons, then slow. Wondering if just running it with less gas will help, maybe the filling to full tank is an issue, will experiment in coming weeks.