Back when the 4013TSW came out I bought none. After I'd fired a little more than 2,500 rounds through mine I noticed some peening down inside the frame's barrel camming surfaces.
I showed it to a rep from S&W one day and he told his own 4003TSW's (aluminum framed full-size .40's) had the same type and amount of peening ... except they'd both been fired about 25,000 rounds each (competition guns).
He said it wasn't uncommon in the alloy guns and usually reached a point where it didn't get any worse. Mine remained the same for many more rounds, but I haven't used that gun for several years. I carried an issued one for a short while, and it quickly developed some similar peening/marking, but like my own 4013TSW, it continued to run normally.
This is my 4013TSW frame at the present time:
My other alloy framed 3rd gen's have similar peening, to greater or lesser amounts (9's/.45's).
The part that would bother me is the missing chunk at the top of the lug on one side of the poster's 4013 (based on what's visible in one of the pictures). Never saw that before.
I wouldn't shoot this particular 4013 further until the factory had examined it and determined it was safe to continue to use.