Trainwreck: Great minds think alike!
I think I've made the connection between the post office at Northampton, Massachusetts and Florence, Massachusetts, as this Postal Bulletin excerpt suggests that Florence became a "station" of Northampton, Massachusetts in 1906:

That's not too far of a stretch to expect that a stamp issued in 1902 could have been used on a parcel in 1906.
So I think that more than likely answers the question.
Thanks for your input.