This happens to my buddy all the time. Something about the way he rides just rattles the shit out of bindings. Damn things coming loose on the board, toe straps falling off, all kinds of shit. I know it's not his setup because the same thing has happened to him when he's borrowed boards from me. I don't know what the fuck he's doing, but it's definitely something he's doing because I don't have those issues with the exact same setup.