I have seen this on Timnehs also on cockatiels,it is normal according to my Avian vet(if you are worried at all take your parrot to an AVIAN vet more expensive but loads better).I had a Timneh called Smokie who died on Christmas eve,she was a rescue bird I had her a few years but sadly even after the vet looked at her she passed away;I really do miss her,as She was not only my friend but also my companion,please if you notice anything at all that worries you with your bird get it checked out