On my latest session at the range, my M&P 9mm was releasing the slide lock if I (pretty) forcibly seated a full magazine. I have not ever had this happen with a pistol before, and it took me by surprise the first time. I was able to repeat this action several times, but only with a loaded magazine, never with an empty one, and only if I seated the magazine with a pretty firm shove. Am I correct that this is not how this pistol should safely function? New pistol with about 1000 rounds through it (and a great shooter, by the way).