None of my other quail have this- yesterday it was a little bit missing. Today its a lot missing. Is this normal? (It is molting season).
Either the bird is being over bred or someone is pulling it's feathers. What is the ratio of roosters to hens in that cage?
Then either the rooster or one hen is picking on that bird. Hens are the source of aggression just as often as roosters are.
No it's not "normal" per se. It is normal to have a few feathers get pulled from the back of the head but not to bald the bird. That is a sign of too few females or bullies usually.
It's normal if you have too many roosters or not enough hens. If you're playing your cards right all your birds should look healthy.