She is fine, when i saw her bitning the rust she rubbed her beak on a perch and chewed on a toy. I was a little worried that she ingested it but i will buy some new bowls that are new!!I was thinking that LICKED iron rust may not be dangerous as iron rust is in our bodies already. But I also guess that a big lump of rusty iron in a bird crop or gizzard would not be good. (That would show up on xray.)
There are binding drugs that can be fed to an animal or person to prevent the body from taking in the metal. Big pieces could be removed from the crop or gizzard. I know this is done with ingestion of lead weights or pellets from animal carcasses (think raptors or bald eagles).
I hope your bird is ok. I would not assume that he is in danger, but it is good to get it checked out.