Earlier tonight I was reraised while holding KK pf so I raised back, and decided to push after getting raised again. The guy turned over AA which held and he won.

Then a few hours later I limp / raised my KK PF and a guy raised again and I pushed, he called with JJ (which ended up cracking KK but thats beside the point)

What I'm saying is at low limits like this (25NL), is it -EV to never fold KK PF? I mean against a virtual unknown is it worth taking the risk when they could very well be playing with QQ or JJ?