IIRC, there was no CVO designation in '08; those models were sold as SE models and the only SE Electraglide was the Ultra Classic; FLHTCUSE. If the bike is an '08 and an extended warranty was purchased, there might be some time remaining and worth asking.
The early 110 motors were notorious for leaking at the cylinder to case seal so I would be looking there for any evidence of a leak. The dealer can also pull up the service record by VIN so you can see what, if any, work has been done on that bike.
You did not mention mileage or asking price. If the price is right and the two year service plan includes such things as cylinder to case leaks and you are not paying for the service plan, could be an OK purchase. However, do your homework; look at the NADA and Kelly values and figure out what you are willing to pay and be prepared to walk if you can't get the deal that you want. It's a slow market this time of year, all the dealers in my area have large inventories of used bikes so take as much advantage of the circumstances as you can and be patient; believe me, people are not lining up to buy that bike.:s