Someone tell me what this is

hey guys so today I noticed that one bottom leave is turning yellowish on the tips. My plant is 33 days in veg mind you I've been feeding her nutes and while I did some of the water spilt on the leave itself. Want to know what it is and should I be worried?
Here's the pics

What are you using as a fan? Where's it's pointed? Are those leaves the ones that move the most when the fan is on?

old leaves get old. maybe an old leaf with an old root that was damaged early? I'd hurry up and cut it away before the other see it, thats what I do and I never see those again till end of flower.