Its only the wrong oil if you want to stay on extended
service intervals, its still a perfectly serviceable oil. You could remove the excess oil then go back for another
service in 10k miles ? ( with the
dealer covering some of your costs as they messed up)
Extended
servicing is in place purely to lower the cost of ownership at the expense of engine wear. Changing oil at 10k is always going to be better than 20k.