Just looks like normal finish wear from the slide...
Might want to check the area on the underside that brings back the hammer. A little smoothing with fine grit sandpaper at the edge should smooth things up.
i am not that up to speed with how different makers make their ammo, but could it be that you were using something with a hard primer? i would imagine that it will not affect the function of the pistol at all but maybe Marty will chime in here and lend some advice.