Huh. I've never heard that. The Kahr pistols are very well made, in my experience. In the course of working at Galco for several years, I talked to dozens of very satisfied Kahr owners. I personally wouldn't hesitate to buy a PM9 if it fit my needs.
I think the main source of PM9 criticism is owners of J-frame S&Ws, whose pet gun has been made obsolete by the PM9.