Hard to say from here and I don't recognize it but that looks a facsimile/stamp as well. The interior of some strokes are lighter than the edges such as the end of the paraph. It presents "wrong" - the scan is not ideal and the ink color odd perhaps. When the scan is color and the ink and image appear the same I get suspicious. Hopefully I am mistaken. The generic inscription only is a suggestion.
You are most likely correct, Eric. No funny business going on, seller discloses strong possibility of preprints and secretarials in a small collection from a serial TTM collector from the era.
My limited interest is now almost dead but I will see if I can find a more likely genuine candidate.