What am I looking at?

keep an eye on it, but don't react now. if it expands, maybe do something, but still most likely take a passive choice. always be certain, first. so many things cause symtpons of nutrient def even when ample supplies are available. when you add stuff, you only make it worse if wrong about the cause. also, looks a bit young. young plants are not as robust as they soon will be. could possibly magically clear up. some water on leaf? could be burn from such things. don't leave standing water on leaves the positives only outweight the negative if you are treating a very specific problem that requires something like that.