We can call the knife filthy, but understand that the lint you see is located in the hidden compartment that houses the springs. There is no way to clean that without taking the knife apart and voiding the watranty. Furthermore, after wiping everything down and cleaning it, I did not find any rust. Just clean metal. Springs break due to fatigue. It is just a fact of life. Not all mass produced springs are perfect, but to the human eye they all look the same. It is a hard thing to QC.
If you plan to carry and use an axis lock knife, expext that compartment to get dirty. You can try washing the knife with soapy water, then wd-40, then oil, but that compartment will still be dirty. You really need to void the warranty to clean that spot...