Propane bleed valve leak

Are you sure your tank is not just venting. Right after a refill if the tank sits in hot weather/direct sun, it may release a little propane to release some of the pressure caused by gas expansion.

It shouldn't do this after you have used some of the gas.

These valves are NOT pressure vents. They should not leak when closed. I had one that did that too. I was able to cinch it down enough to stop the leak but I was very apprehensive to crank on it too much. I later let it get low enough to remove the valve and replace it with a new one.

First thing I woudl do is try to tighten a bit, WEAR GLOVES (heavy leather) or use pliars. DO NOT go "Gorailla" on 'em

if it still leaks, Visit a propane wholesaler with a service dept.