I've been in a house that was newly built 2 years ago. In about the last two months, I have had 3 separate 3-way switches quit working (all controlling different fixtures)

The first one would not switch off unless I forced the switch all of the way down. With the second one, the light got stuck on, no matter what I did with either switch in the circuit. With the third one, in one position things worked fine, but in the other position, when I switched the other switch, the light would cut off in the middle then back on when the switch was up or down. The only brand marking I could find on the switches were the letters "ps"

I have replaced all three switches and everything is working as it should now, but I am concerned as to what might be causing these failures.

Could this be that the electrician just got a bad batch of switches or used cheap stuff, or, could there be something wrong with the overall circuit that would cause them to fail?

Thank you for any insights you may be able to offer!