You would think so, but if you look closely at the large picture on the S&W site, the stamping is the same as on mine - ".38 S&W Spl." No +P. Yet the text indicates they are.
With the all steel cylinder and barrel, I wouldn't hesitate to use a limited amount of +P in it. Certainly for carrying, it should be ok. I plan to use only relatively light reloads for practice with the occassional +P and carry +P.
You do raise a good point. Maybe a call to S&W concerning this specific revolver is in order.