Wert - I had to enlarge the screen 300% to see anything.
I do see a red spot on the stamp you did not circle, but not on the one you circled in yellow. I used two arrows to indicate the red spot.

For some reason, your images are far from the actual colour of the stamp. making it difficult to see what you are trying to show. Here is a scan of one of mine.

I do not have the red spot on any of mine.