It is OK, isn't it?
Dd fainted at an activity last night. She's only ever fainted before when she was ill. She's lean, active (but not over-active) fit, healthy (AFAIK), good appetite and reasonably healthy eater.
So it's nothing to worry about, is it? The occasional faint is a normal part of being a teenager? I never did it, though several of my classmates did.