i used to work in the passport agency years ago,for a start the laminate shouldn't have come apart as it should be checked before it was sent out,so you could have a complaint that its faulty even with normal wear and tear.
Anyway though a photo plays a part in security obiously,the other major part is the bar code in the passport that is the part that is scanned in,and thats what comes up on the screen to show if you are a wanted criminal or not lol,if thats damaged then you may get a held back.
Stick it back in with some prtitt stick and act dull if they say something!!