Question About Malden On The Hudson, NY Cover From 1880

I have this cover that was from Malden on the Hudson, NY, sent June 21, 1880. The problem is that both Helbock and Jim Forte's site list the earliest "Malden on Hudson, NY" at 1907, and an earlier mention of just "Malden, NY" from 1826-1907.

This cover has "Malden on the Hudson", and the other only mention of "Malden on Hudson" is from 1907, 27 years later!

Would this now be the earliest dated cover from Malden on the Hudson, or ??

Notes: I uploaded two images, the first being as scanned (very light), and the second being color/contrast manipulated to better view the CDS details. Also, thanks to John Becker for the suggestion to check the Jim Forte Website as well!

Jim Forte's website, Postal Guides, and Official Registers agree (or do not contradict) with the name chronology you give.

More specifically, Postal Bulletin #8392 dated Sept 9, 1907 notes in the first column the name change from Malden, Ulster Co., to Malden on Hudson effective 28 Aug 1907.

My guess: the postmaster (having a very small office) had to order his own postmarking device and chose to have the extra text added, no doubt contrary to regulations. I'll bet he didn't use it very long.