Minor burning, I wouldn't worry about it.
Can be caused by water splashing on the leaves or when two leaves sit on top of one another.
Sometimes caused by nothing at all and are just "funny" leaves.
If it is only one or two leaves there is no real problem, if it were an issue with nutrition or pH etc, more than 2 leaves would be showing symptoms.
Remember too, no plant will ever have 100% perfect leaves, 100% of the time.
Cheers, Organoman.