New to This and Need Feedback

Just started growing bc I got my med card. I bought some clones awhile back from my club and everything has been going great. The other day a buddy of mine gave me one of his clones that he SAID was mite free. I checked it over and didnt see anything but today when I was down in my veg room and taking a closer look at it I noticed an itty bitty tiny bug and when I moved the plant the bug ran away to hide. I only saw the one but now Iam worried that my other plants may be in harms way??? Also threw that plant out.

you can't see mites "run away" they are the size of pepper specks if not smaller even.
you most likely threw away a perfectly healthy plant