Drive the car for 5 miles, then have it remeasure the oil while you're stopped and idling on a level road. Measuring the oil while driving doesn't seem to work, as I learned when I had an unfortunate underfill and then overfill situation both on the day before a track weekend. Anyway, if the car still says overfilled after measuring while stopped, take it back to the dealer. I'd be worried about foaming as well, and getting them to fix their own mistake is cheap insurance against larger issues. If you have a problem later and tell the dealer, "This is your fault, you overfilled it!" and they ask why you didn't either fix it yourself or come back so they could fix it, what would you say in that situation? Take the proactive approach.
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