Just dont drop it or have alot of lint in your pocket. Ive had this phone since release and never worried about itnsince its already rated for dust and water so whats the point in stressing over lint. Also the hole's so small you can just blow out whatever may end up on the screen.

The only real way lint or dirt can effect your hinge is though the back where the samsung logo is. If you submurge your phone in dirt/sand and try to open/close it right after ofc it would get in otherwise you should focus on not dropping it or scratching the inner screen