If you're worried about the possibility of a stolen gun, give a call to your local police department. They should be able to run the serial number of the gun, and find out if it's been reported as stolen.
Now, not to jack the thread, but a general message to my fellow shooters:
The single most important thing you can do as a gun owner is to have a record of your serial numbers. It is the ONLY thing that will re-unite you with a stolen firearm if it becomes stolen.
Once reported, the serial numbers of stolen guns are entered into the records system, and they NEVER are removed--unless the gun is recovered.