Its a 92 prelude si

New oem clutch, pressure plate, tob, flywheel and slave cylinder...well they were all new 6k miles ago and im now having problems

The problem is sometimes going into first while i release the pedal the clutch slips and i hear a loud screech/whistle that sounds like moving a chair on a wooden floor. It only does it in first and it only does it one out of every ten times or so. I cant make it do it either...so i took the clutch out and has lots of tiny tiny pits in it with copper showing underneath, Its all smooth minus a few small rough spots that look like they have grease on them. Everything else looks fine. Is it the clutch? Or is that normal wear?