check your forward pressure, what can happen is the toe and heels of your boots can get worn down (especial if you walk on concrete with them) which can change the forward pressure cause pre-releasing. Put your foot in your boot, then click into your skis and try and twist your boot, if it wiggles (or even pops out) it's most likely your forward pressure. To adjust forward pressure, just move your heel piece forward on the track a click or two (until it stops wiggling, but you can still click in), so bindings it's turning a screw with a phillips head screwdriver, some you have to lift a tab in the back of the heel piece with a flat head screwdriver and push it forward on the track (with these there's usually some sort of indicator if the binding is locked in place or not - it's usually just a little window that has a color (most of the time yellow) that moves up and down - if you can see the color it's locked. If you have FKS, you have to use a wrench or pliers to turn the "arms" that connect to release to the baseplate.
