So, our new postmistress called this morning, as promised. She called her District Office to inquire about progress. DO expects to get the zip-code request out "by the end of this week."
It usually takes 2-3 weeks for National to received and act on the request. Then the database will be updated (and info will start farming out through interlinked databases.)
She offered to call me as soon as she knows what the zip is. (She really is quite nice and helpful; just ... un-empowered.)
Progress, of a sort, I guess.