If you don't see any leaks from the gas valve to the burner, that section that is charged with gas while the frig is in gas, check the valve body itself. That valve is a 2 stage system and the second stage may be leaking.
If not turn all gas appliances off. Turn the gas tanks off and let sit overnight. Then open the gas tanks. If you hear gas flow when you turn the tanks on you have a leak in the piping of the trailer.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles