Upvote:3
It's not a problem. It's likely an artifact of the production process. I have exactly the same in the four Norwegian passports I have lying around.
Not as extreme, and to a varying degree, but still clearly visible.
I should also note that I have pages with tears (from stapled in entry notes), crossed out visas, overlapping stamps - and it lived in my inner pocket for four years, so the gold trim is half worn away. Yet I have never heard a single word about passport being worn out.
Upvote:5
This is not an issue. Some smudges and marks are common and increases upon usage. As long as the ID page is ok, this is not at all a problem.