Premature Slide Lock?

[BMI]

I purchased a new PM9 (all black, night sights) approx 2 weeks ago.
The second Kahr I have had, the other being years back, a K9.
Love the gun, put 350 rounds (mixture of HP, Magtech FMJ and Federal Champion FMJ) through it with no problems, then a premature slide lock in the middle of a magazine. I dropped the slide and carried on for another 50 rounds with no problems. At this point I could not swear to whose fault mine or the gun.
Anybody else had this problem?

[enscore1]

I had that to occur once...my thumb bumped the slide release (limp wrist).

[BMI]

I had my wrist etc. locked pretty good, I think my thumb/s might have moved up to the slide stop. I put the Pearce extension on the 6 round "flush" nmagazine, it pinched my pinky no end! I have big hands.