Here’s what he had to say (I added the link):

Etymologically, epigraphy means “writing on” (i.e., a surface, etc.) but I think yours is a good definition. The best modern work on epigraphy is Armando Petrucci’s book La Scrittura, which was published in English as Public Lettering — a better title than the original, I think. The opposing term is bibliographic. When I consulted the American Heritage, with whom I’m associated, I discovered that we didn’t have the relevant sense for that word. The OED does give a sense for bibliography as “the writing of books,” but says it’s obsolete. My impression though is that this sense is current in this particular literature, in several languages. (I’ll see whether I can get this sense included in future AHD editions.)

So, maybe my email will result in an addition to the American Heritage Dictionary. You’ve got to admit, that’s pretty cool! Thanks to Geoff for letting me post his email to bradlauster.com.