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Don't remember if this question got resolved in the list discussion.  At
the risk of covering old ground,  here's a thought about a possible
source of gluten in supposedly "safe" vinegars which could be causing the
reactions some of us have experienced:

I don't know how vinegars are made in current commercial production.
However, the old fashioned method used a "mother of vinegar" which was
basically a yeast culture much like sourdough starter. This was,
according to an old recipe I've  looked at,  cultured on a grain mash.
If this method is still in use, the vinegar problem could be a similar
problem to that involved with Rice Dream where they grow the enzyme that
they use to break down the rice into syrup on barley. Technically
speaking, barley isn't an actual ingredient of the final product. The
ingredient is "rice syrup" or some such. However, enough of the grain
fraction comes along to create a problem for sufficiently sensitive
individuals (such as myself).    My theory is that with vinegar, however
they get the yeast into the stuff these days, probably the grain product
is coming in by that route.