Fairly young rigs with low miles could be the result of a couple of reasons. Good possibility the first owner didn't know what they were getting into but found out they enjoy every second in the coach but it just doesn't fit their needs and they traded in for something bigger or better. The other side is owner that just could not get make it work and sold the coach back to the dealer. The worst case scenario for the potential second owner is the coach is the Queen of the service center have spend more time in for warranty work there than on the road and the owner gave up.
Baring the worst case, 10K on a 2 or 3 year year old is about average for weekend/summer vacation owner which is how I would describe myself. At 13 years of service and 69,000 miles my yearly average is only 5,300 miles. Close to what you're seeing.