Wtf?

Slight burning from a soil mix that is too rich with nutrients and some mechanical damage to the leaf tips from hitting the soil or edge of the pot at night time when the leaves hang downwards. Both issues are nothing to be worried over, the plants will grow just fine, however, there is no need to feed them for another 3 weeks at least. At this age, in good soil, there is no way they could be suffering from any sort of deficiency. Remember too, no plant will ever have 100% perfect leaves, 100% of the time. If you are new to growing, visit the Mandala Seeds website and read their "grow guides", it contains a lot of excellent information designed for European growers..........you will learn a huge amount of knowledge!