If the regulator was in good shape in 2009 and the guy who serviced it did a good job, chances are it will be fine. Cycle the regulator a couple of hundred times before you do a VERY thorough inspection. The soft bits will decay even if you don't use the regulator, sometimes faster because you haven't. Good O-rings should last for close to ten years before they become significantly brittle, cheap ones are prone to early brittleness and tend to permanently deform without use. Ditto seats and diaphragms.
If there is any question about the performance, get it overhauled. If you don't have the skills/tools to do a thorough inspection, get it overhauled. Or not, if you like dancing on the edge.