This isn't uncommon in my experience. I think some of the posters here are used to playing at higher limits, because I see people do this kind of thing much more often than I see quads.

A decent player might fold JJ or QQ, but a typical micro player is likely to call or raise with many hands. The likelihood of a player at 1/2 paying you off (or capping) on the river with an inferior hand seems much greater than the likelihood of his having quads.