The posters that are worried about a ND, or are saying to send the gun back worry me a little. Not only is this fairly common with some handguns, but it is a simple matter of physics. If you slap something hard enough it will giggle things around, mainly the slide stop.
The pistol will not fire if you keep your finger off the trigger. To me, if you do not understand this, you need more training.
good and safe shooting, bdb. BETTER TO BE CAUGHT WITH ONE, THAN WITH OUT ONE