It's deformed. The right side of that tab (in the first two pictures) should be straight and tucked under the sear housing block. Not sure what would cause it to come out unless it was messed with and someone pried that spot to get the sear housing block up.
Not a crucial area, though, there is nothing going on there. Nothing under the slide, just a smooth area where it rides along the rail insert just behind it. I'd say smush it in with a little heat or just leave it be if it's not impeding slide motion.
Or if you're the fretting type, send the pics to S&W, but it really does look like a side effect of some hack prying the SHB up.