Yeah the regulator is equipped with a pop off valve that prevents you from using high pressure bottles (those pressurized above 2500psi). Sounds like regulator blew out or someone over presurized the K bottle. Take the bottle and regulator back to Northern and have them check out both of them. Sounds to me like the pop off valve is doing its job. If you've run that much gas through the regulator it probably needs to be replaced or rebuilt anyway.