Passed my PSM-I (76 of 81 points)

Hi,

I've got a question regarding my PSM-I-assessment.
I passed with 94%, but my goal was 95% (I heard that when passed with 95% I would be allowed to do a Scrum trainer assessment).
Now my question is: my result says I got 76 points of 81, but as I remember I answered 80 questions.
If it were 76 of 80, than I would have the 95% I need.

How is it that there are 81 possible points with 80 questions?

Thanks and best regards,
Stefan