There's no way to know for sure if that screw was put there by the guy or not. If say there were 4 screws 1 in each tire then yeah he probably did do it. That not being the case, you could've easily picked up that screw anywhere enroute to your hunting spot. I myself would dismiss that and just consult the landowner about him breaking the law. Of course then, there could be retaliation from him considering you'd be a likely suspect as the guy who "ratted" him out.