Firstly those aren’t preflowers as
@MickFoster has already said they are stipules.
But I can hosnetly say I’ve never once paid attention to those stipules for anything related to my plants health.
however you do have some bugs which could have caused the issue.
your plants look a decent shade of green and heathy besides the leaf miner issue.
I would honestly say stop worrying so much and just let it grow.
Look to your leaves first for the signs of issues.