Seedling lost leaf

Dont worry growmie, that's actually not a problem, or it's so minor of a problem it wont matter. however what i see is that the seedlings are stretching, this leads to what you're seeing (stress, stretch) . This is what you should do : lower your light to 50 or so cm , then lower it slightly a bit every day or so until you're satisfied. It might look a bit too close, but often times you're around 40cm away from the plant ! then you want to basically fill the last few cm of the pot with your medium , that' so the seedlings are supported better and compensate for the stretch a bit. Hope this helps ! 🚀