I think there is over-inking at the top, with oxidation.
Here is an example I have, without the oxidation.

There was an article in a recent issue of BNA Topics on similar blurry printings of the 3c Small 6ueenQ, but don't have access to my copies at the moment.
Buy the way, your stamp is Unitrade/Scott #41. With the 1897 date, I would guess is is perf 12.25. Most of my 1897-98 dates have that perforation.