I am not a Revenue collector, but sometimes at a show going through the 1/2 price box I see something nice (artistic) in the revenue side (especially Newspaper/Periodical section) and pick it up. I recently purchased a PR120, PR121 & PR123. Nice color, good centering, LH with OG. While inspecting the gummed side of the PR120 & PR121 I saw what I thought were blind perfs (both Horizontal & vertical, intersecting). When I inspected the design side I could not detect any indication of a blind perf. (I tried to get a scan of the gummed side but it did not provide any detail sufficient to view). My question: is this a normal aspect of revenues and could it be caused by an overlay imprint of perfs when the gum is wet(or are the sheets perfed then gummed).

The stamps are normally perfed, but the blind perfs are seen within the design field on the gummed side.