Series 2 Question Paranoid Perfectionist

I exchanged my first Series 2 controller earlier today and got a replacement from GameStop. I went to swap out the D-pad and saw a white fiber in the gap which has now been made irretrievable in my efforts to get it out. The controller works fine and I'm afraid if I exchange again, that might not be the case. Is it a danger or worth keeping if something gets into the controller like a fiber which may have been there since manufacture?