Hi,
I have a plant around 15 days old also. Is a bit more evolved with a node (but it doesn't matter). Due to high humidity I got around 3 of those edges upwards on some leaves. Not the whole leaf. In my case I guess is the humidity. How offend do you water? What is the temp(min max)? What soil do you use? Do you use any nutrients?
I write this not as an explenation but becouse the more experienced guys need some info before telling what it is. I am curious also.