One funny leaf is nothing to be worried about.........no plant will ever have 100% perfect leaves, 100% of the time.
It is quite common to get the odd funny leaf on every plant, it is just a slight deformity, nothing else.
Don't worry mate. It isn't a problem at all. Normally the first leafs tend to reflect the plant's feed and water first balance and some little things with a little curled and brown spot isn't really any problem of lack or have in excess any nutrient. Keep the good work and relax.
420 Always...cheers