What do you think? Opinions?

The other day I lifted up my dome and seen a ton of spider mites on my cuts. I have no clue how or where they came from and they were only in the dome no where else. Other seedlings were next to the dome... after thinking I was wondering about my rapid rooters. The first one I picked up I saw this in the opening? What do you think or is that normal? I didn't see it in all of my cubes it's not thick but I can see with the naked eye?
These are all the same Rapid rooter

Bump! Looking for some help need to know if I should pitch these and grab some new one somewhere else

Cut your loss. Clean area throughly. Start again.