At the first oil change on my '06, the washer was stuck to the pan. It is very thin and has some sort of composite material on it that is blackish in color, so it was very difficult to see that it was stuck to the pan. The skid plate sort of gets in the way too.
It took me quite a while to finally get it to bust loose after prying at it with a screwdriver and knife blade. It's probably a good idea to make sure that it's not stuck there and replace it with a new one - eventually.
I installed a Fumoto valve, so I should not have this problem for the life of the vehicle.