Germany 3 Pfennig ,1889 - Ink Smudging ?

This, Germany 3 Pfennig ,1889 has brown ink smudging at left and right of the number at center,the left frame has a similar look. The brown color is under the cancel which is also peculiar . Could this be result of a printing error ?

Nothing says those marks were on there when that stamp left the printing firm .....so no value .

I suppose that it could just be dirt or not it is not easy for me to say.
I'm still puzzled how can this brown coloring been applied there after the time of production, if it wasn't made in the printing office. If you examine the stamp image closer, you can see that the line between 3 and word pfennig is continuing under the "10" of the date of the cancel. Similar smudging could be seen at right on the leafs and the decorative elements, over S in the lower inscription and in right top frame. Isn't there a chance how ever small, that it had occurred
during the printing process when it still had not been dried ?

The stain could just as easily have occurred in an office or house before the stamp was stuck to an envelope.

did it soak through the back?

I can't say ,it is possible. The owner which offered the stamp to me said that there were small ink traces on the back,but he didn't send me images of it.