Have no idea what that is. You need to provide more info. Where do you live and how are you growing this plant?? I think I would cut off that brown leaf, but I need to know what's happening with your plant.

Jane

Sorry did not see your answer, I am in Lima Peru, so weather conditions are like min 15C and max 26c, they are in a big balcony no direct sunlight. This new leaves just grew differently...and the brown showed and expands but very slowly. It has only affected some leaves the other seudobulbs and leaves are ok. roots with green tips, healthy looking.