So wikipedia says this gun stopped being produced in 1999 wikipedia is user submitted info and as such is not always 100% accurate the info I read states that the Canadian royal mounted police as well as several military's still used this pistol until 2011. So a 2009 produced unit still falls into the era that S&W would have been producing them.
Also in the buds item description it says these were display models and per SW has to be sold as used even though they're new, but as display models could have very well been displayed at trade shows aimed towards law enforcement. I will copy and paste the article that talks about the run of production in a separate answer as we are limited to so many characters in our response.

The Smith & Wesson Model 5906 is a stainless steel, Double/Single action, locked breech semi-automatic pistol introduced in 1988 by the American company Smith & Wesson. Design details
The 5906 is constructed entirely from stainless steel and is thus extremely resistant to harsh weather conditions. The firearm was factory-shipped with a magazine disconnect feature designed to deactivate the trigger if the magazine is not fully inserted. This is nearly unique since it is a double action design. The 5906 comes standard with either a 10, 14 or 15 round magazine.
Other features include a pinched barrel designed for tighter slide lock-up, ambidextrous safety levers, spur hammer, a one-piece Xenoy polymer wrap-around grips with either a curved or straight back strap, and a choice of either low-profile Novak 3-dot sights available in either fixed or fully adjustable for windage and elevation.
Like most third generation Smith and Wesson semi-automatic pistols, the 5906 features a combination safety lever and decocker mounted on the slide, a plunger type firing pin safety, a magazine disconnect to meet the needs of law enforcement agencies and a pin mounted, pivoting spring actuated external extractor.
The 5906 design is famous for its "finger-step" squared trigger guard that is similar to that of a Lionheart LH9. The distinctive trigger guard was later changed to a similar round trigger guard for ease of production because the pistols had recently become popular with law enforceme