Yes there is something called slip claw,Slip claw is when the rear toe is pointing forward along with the other three toes & is usually discovered when youngsters leave the nest for the first time & is something that has occurred during the development of the chick,so your grey never jumped on the perch !!I advise a vet's visit ASAP To help your bird, the vet will probably use a thin strip of sticky tape to secure the toe to the leg, The bird will need this for a couple of weeks.