[F-five hundred isn't that old though! Aziraphale's expression looks rather shocked though, because fifty...

To not even be a century old, this had to be the youngest angel Aziraphale's ever met--]

Goodness, that is incredibly young! [In which case, this angel posed absolutely no threat to him, and he therefore had nothing to hide.]

I'm sorry, let me introduce myself. My name's Aziraphale-- I'm a principality myself, which is why I was surprised to see another angel here.