Seasonal adjustment of gum was a subject for correspondence between the 3rd assistant PMG and the bank note companies at least as early as 1870. It was designed into contract specifications back then, but without specifying the details of its manufacture and character. Someone with more knowledge of the earlier issues can tell you whether or not this came up before 1870, but I tend to think that it did.
The problem of getting a gum that would stick when it should and not when it shouldn't was always a tough one to lick.
