If you got a tank with the new J valves, then it's possible. Those valves are designed to let out propane slowly. If you cranked it up really quick, then it could have shut itself off and you have to wait a few minutes for it to "reset." If you hear a liquid like sound sloshing around in there, then you still have propane. Better yet, weigh the tank and then subtract that weight with the tare weight stamped on the bottle itself.