I wonder if being a master distiller requires a license or if its just one of those ceremonial titles you carry forever. I can call myself a Lawyer even though I do not practice -- simply by virtue of the fact that I hold a license and in theory could. Ambassadors are often called by that title long after leaving their post. Maybe being a master distiller is like these. Once you masterfully distill something you are called master distiller for life.
Interesting thought as Henderson, in particular, has certainly distilled some impressive things and I believe Angel's Envy when they plan to do so in the future. Others' claims are a bit more tenuous, though.