Cockatiel with dark spot on tongue

by Becky
(Washington, DC)

I have a middle-aged grey cockatiel male who has been an excellent breeder. I just noticed that he has a dark spot on this side of his tongue. Should I be concerned? He currently is under some stress because his mate hurt her foot --we are keeping her in a small fish tank so she doesn't have to climb or perch. This temporary living arrangement is abnormal for both of them.