Not only is that pretty common and of no concern, there are some of us who tweak the Slide Stop Lever just so that it's easier to make the pistol do that every time. I've done it to all my Glocks because it make for a really fast mag replacement. If by chance, it doesn't drop the slide, I just hit the Slide Stop Lever. It's so much faster than the overhand method and if you practice it, it becomes second nature.
“Remember, no matter where you go, there you are.” - Buckaroo Banzai 1984
"When you find a find a big kettle of crazy, it's best not to stir it." - Dilbert 2009