cybersix said: 
I read somewhere to cut long leaves a bit, to give more strenght to the roots. Does it make sense?
The seedling looks normal for its age to me. No, it does not make sense to cut long leaves to give strength to the roots. It would most likely do the opposite. Remember that it is the leaves that make (by photosynthesis) the food for growth, including root growth. So if you shorten the leaves you limit the plant's ability to make food for growth, including growth of the roots.
