Date Obscured

I have the Sweden Scott #1904-1906A booklet commemorating the coronation of King Gustav III. The booklet is engraved by Slania. Just below the largest engraving on the sheet is the year of issue 1991. However, on the copy I have, the year is obscured by an ink blot. I want to document this in my inventory, but don't know how to classify it. I can't tell if the blot is the result of a flaw in the plate or a printer's error. Anyone have a suggestion on how I might determine that? I also don't know if something like this can negatively affect the value and collectability of the booklet. Any advice? Thanks.

A scan of the item would really help

My one is "normal" so yours must be special in some way. Hope so anyway.

Imperf13, there is nothing like you describe in the Facit Specialized (Scandinavia) Catalog. The booklet pane (3 stamps + label) is Facit #H419, and follows #1707 in the catalog.

It looks like my notes were wrong on this one and I didn't double check before writing this post. There is a blemish of some kind on the stamp just to the right of the year. In the photo posted by @scotzm, the blemish would be to the right of the year and below the arm of the throne. The blemish is about the width of the arm of the throne. It appears to be excess ink, but the engraving is okay. I guess I solved my own problem. I'll work on my note taking. Thanks to all who took the time to respond.