iPad Seem to have rubbed off a bit of the screen adhesive when cleaning the screen

[Ploid]

A month or so ago, while cleaning the screen of my iPad Pro 2018 for new screen protector, I wiped off a dark substance at the corner of the screen bezels. I used the official Apple polishing cloth along with the microfibre cloth and alcohol wipes that came with Spigen screen protector. At the time I thought nothing of it, but now I think this is pretty unusual. Should I be concerned?

 

[alFR]

I believe it's called "dirt".

 

[MonksAndDruids]

I recently purchased the iPad mini 6 and right out of the box, I can see a bit of dark grey/black adhesive on the top edge where the screen meets the frame. I’m not too bothered about it but it might be that.