Has anyone seen this before? I have had this plant for about 6 months and it finally got 2 new leaves! They were looking great and then I woke up one day to purple colouring on the back of the leaves and brown edges. I keep it in a south window and let it dry between waterings.

At first it was just the bigger leaf of the two with the odd colouring, which has since faded and improved a bit, and now the smaller one has it.

Thanks!!