I have a gen 4 Glock 17 that did the same thing when it was new. It would barely hang out of battery if I very carefully eased the slide forward. Now, with about a hundred and fifty rounds through the pipe, there is still a noticeable tight spot just out of battery, but the slide does not stop there.

I also have a gen 3 Glock 36 I bought used. Same tight spot just out of battery. I've noticed the same tight spot on every other Glock I've handled. That's about the same thing I'm seeing with the Shield.

Polishing and radiusing the sliding surfaces will probably eliminate the sticking, (as will putting a couple hundred rounds through it) but the slight tight spot will likely be there forever.

It is apparently normal. Maybe S&W has some way to address the problem. If they do, great. I may inquire about it myself if I find out that they do, but in the meantime, it's not a safety or reliability issue so I'm not going to worry about it.