Well picked up by you.
Personally I consider mine just an EFO or FIDO
(Errors Freaks or Oddities)
For it to be listed in a catalogue, it would have to be a damaged printing screen, which is not.
Deserves to be on an Album page with an explanatory note.
Keep scouring those stamps !
PS: I have noted other members here, refer this type of thing, to "Ink Pull"