So I recently repotted this baby from its mother philodendron birkin. It seems to be healthy so far, but the first new leaf it’s grown has brown on the bottom side of the leaf. It’s almost like the brown is a birth mark as it grew in with this mark. It didn’t develop it due to watering conditions. rest of the plant is very healthy. Does anyone know what this could be from? Is it a health issue ? I thought maybe lighting but it is in medium light, just like its mother plant.