m0useanswered grow question 3 years ago If it's only on one leaf I would not worry to much about it.
It could have been water damage from being wet like you said and then getting burnt from the lights.
Or a splash of the nutrients.
Don't panic if its just one leaf and keep an eye on it.
Don't remove it as well, if it gets much worse on that leaf then it will help us determine what it could be.
Good Luck!