Walk Behind Lawn Mowers

I purchased a Husqvarna self-propelled walk-behind mower on 4/28/2016. Yesterday, the right rear wheel became loose. It will not hold height-adjustment, and does not see to be engaged in the differential, as the wheel spins freely, unlike the left wheel.

Is there an authorized service center in the Grass Valley/Nevada City area of California? Zip code is 95945

Would this be covered under warranty?