What tends to happen is once they have fully faded, they will get some of the dark streaks and patches back if they are stressed or something changes in their tank. Even breeding behavior will bring the dark makings back but once they get a bit bigger, this stops. It's most common when you buy parrots and put them into your own tank. This change seems to trigger a fully orange parrot to be streaky a day or so after your get it. Most people who are new to keeping parrots or cichlids that fade, tend to freak out a bit. It's usually nothing to worry about but testing the water is always a good idea.