Sounds like he was there for a deal on something he wanted, versus filling a need.
Regardless of how awesome Glocks can be (Love my 30), I think that no collection is complete without at least one wheel gun. Sounds like he found a better deal on a Ruger than he could find on a Glock this trip to the show circuit.....
Enjoy Phantomak, it is a fine piece. I think there was a period of time that Ruger believed there to be a design issue in the area the barrel and frame met, but that ended up being incorrect. (Ended up being an assembly issue due to a temporary process change. I think this is why the Super Redhawk line of guns came about, they re-designed the 100's with a beefier frame before they found the process issue and corrected it.)
As mentioned earlier, these badboys were built to last. They were designed to replace older service model weapons that had demonstrated limited life expectancy when using .357 magnum loads. The GP100 line was introduced as something designed to handle .357 magnum loads "indefinitely"....nothing lasts forever, but odds are this baby (properly cared for) will shoot straighter than you can and will be aroundfor longer than you.
If you bought this badboy NIB, you shouldn't have any issues. If you have any doubts, call Ruger customer service and they can compare your serial number to their records to ease your mind...
In any event, enjoy it. FWIW, I think you made a sweet deal on a great revolver.......(cheapest NIB I could find was $450, plus shipping, plus the paperwork fee from your local FFL...)