Thanks to all who replied so promptly!  Turns out it was a leaky valve stem.
Thought this would be a nightmare to replace...but apparently it was a
standard valve which was replaced at a local propane shop for 36 bucks
installed.

Dane Tessler
87 Westfalia 138K
Treasure Island, FL
http://members.aol.com/Dane714/westfalia.html