If it’s a briar pipe, the wood shouldn’t be gummy. It should be dry and hard as a rock.
Some pipe makers coat the inside of the bowl with a substance that is supposed to protect the wood from the heat while you break the pipe in, and build up a cake. Paul, could the stuff you’re mentioning be some of that substance that somehow wasn’t fully dry when they put the stem on the pipe?
I also saw your other thread about the screw in the stem–I’ve never heard of that, though I’m familiar with the filter pipes mentioned. If I can ask, between the screw and the stuff you found in the stem, just what kind of a pipe is this that you have?