The top round being dragged a little forward isn't anything new, nor is it even really a "problem".
Yes, if the bullet nose goes too far ahead of the frame cut in front of the mag well, it can result in the top round being pulled loose/free of the lips, but that's usually only a "problem" when removing a mag to top it off. Just replace the top round bumped loose when you add the "top-off" round. (If you "top-off" your mags, that is.)
This has been observed to happen more often with single stack 9/.45 mags, but it can also happen with a double stack mag. There's usually just more friction and less "wiggle" room between the top round and the slide's pick-up rail in a single stack mag situation.
FWIW, the first several times I noticed this happening in my own 3913 and CS45, many years ago, I chambered my guns on the range, deliberately inducing the condition where the "next up" rounds in that forward displaced position occurred, and repeatedly fired the guns that way. I couldn't ever get the condition to result in a feeding stoppage during live-fire, so when the armorer instructors said that it wasn't a problem, I believed them.
It seems the forward displaced rounds are supposedly pushed backward due to recoil and the slide running rearward, so they're apparently back in the correct position for the slide's pick-up rail to find them and feed them up the feedramp during live-fire.
PS - now that you've "adjusted" the lips of your CS9 magazine, if it were
me, I'd discard that particular mag and chalk it up to the results of trying to fix something that didn't really require fixing, and order a new mag.
If the feed lips are now too
narrow, it may cause occasional feeding problems like nose-dives, because the rear of the cases won't be allowed to rise up from the narrowed lips in the proper timing during recoil and be released to slide up the breech face. Conversely, if the feed lips are spread too wide it can result in
real live-round stovepipes and/or early ejection of live rounds during recoil.
I wouldn't even bother trying to "bend them back", since you don't have the Go/No-Go specs for the lips along their length, but would just consider it a lesson learned.
That's just me, though, Even as an armorer I've learned a few lessons the hard way in my earlier years as a younger armorer. BTDT, myself. (I kept a few of those ruined parts for a while, to remind me of jumping the gun and trying to "fix" something before I'd actually identified whether it was the
right problem, or was even a problem that required "fixing", at all.
)
Just my thoughts.
Sometimes Midway has CS9 magazines on sale for approx $26. I just checked, and they're the regular retail price there, it seems.
Smith & Wesson Mag S&W CS9 9mm Luger 7-Round SS - MPN: 192710000