Liquid Propane Spurting Out of Regulator

[Midnite]

My wife and I took a quick overnight trip from Anchorage to Seward last weekend, and I noticed something that kinda scared me with the propane.

The camper is a 1970 Alaskan, and I have a brand new propane tank hooked up to it. In the morning in Seward I fired up the little catalytic heater and started breakfast on the stove. The first odd thing I noticed was that the burner flame would slowly shrink down and then eventually flare up a little bit and go from blue to orange. It would then repeat the process. A short time later I opened the back door to go outside, and just by chance looked down at the propane bottle. I noticed that the round metal piece on the camper's hose connecting to the tank (pot metal thing sorta shaped like a hockey puck--there's one on my BBQ as well) was covered in thick frost. Anyway, right at that moment a little spurt of liquid propane boiled out of that hockey puck shaped thing with a big hiss! That made me pretty nervous, so I shut the valve on the bottle immediately. Obviously the propane stays off until I fix the problem.

Does anyone know what's going on with that? The only thing I can guess is that the hockey puck thing is some kind of a second-stage regulator, and probably needs to be replaced (I'm sure it's the original that came with the camper in 1970), but I thought I should ask here first.

Thanks,
Mike