I assume you mean the curling on the leaf serration. That can happen for several reasons but I don't think you need to worry about them at this point FYI. Yours just looks like a single leaf so I wouldn't worry. Stress will induce the edges to curl in different ways due to heat stress, root stress, water stress and I'm sure others. One of the windows into reading your plants is learning what the plant is saying to you by its leaf. A single leaf though could just be a blip and not anything too concerning.