Sales Agreements: Do You Have to Pay More Money if the Dealer Underestimates Licensing Fees

My question involves a consumer law issue in the State of: WA
After about a month that I purchased a new car (paid in full), I received a bill for under estimated licensing fees.
Am I legally required to pay the difference to the car dealer?

Sales Agreements: Do You Have to Pay More Money if the Dealer Underestimates Licensing Fees