Hmm... I understand why you say that. But the thing is, my Fairphone has been send to the repaircenter for this exact reason. I got the same one back because there was no fault present in the screen or phone.
The funny thing is, the same thing happened for other people:
Notice the guy saying: "oh, it actually shows up on a screenshot"? And i don't see it there too. Edit: actually i do, but indeed much less then when taking a actual photo.