Almost every gas mag I've had, pistol, rifle, and PDW has leaked. TM, Marushing, KWA, KSC, Tanaka, it doesn't matter. The ones that haven't leaked are probably going to leak this spring.
In most cases the leak is easy to fix and stay fixed. The Gen 1 WE mags are a bit finicky so if you're buying new it's definitely worth the extra legwork to get Gen 2s.
Airsoft, where nothing is hurt but feelings.