I cannot speak for the Routan or the 3.8 liter motor, but most of the time when you do your own oil changes, the amount of oil that comes out seems lower than what it should. Abviously there is oil still hiding the various knooks and crannies of the engine, plus clinging to every surface in the engine. Also, most driveways are on a slight incline for drainage, so there could be oil in the pan.
I'd be worried if, when you check the oil when refueling, if there is evidence of oil disappearing. My Toyota has 156,000 miles, and it is starting to have oil disappear between changes, where-as it didn't do that before. I'd check the oil level afer running the engine a minute or two and shutting it off. Fill it to the line, and then check at every refueling to see if it is disappearing.
One other thing - the only service that is supposed to be required at dealer of purchase is the 90 day check-up. Any of the others can be done at any Volkswagen dealership.