She was not covert when she worked at CIA Headquarters. Shen commuted every day from home to work in Langley. Covert agents don't openly work in Langley. Formerly, she was a covert agent when she worked for a private firm in Belgium. She was not covert when she was assigned to the US Embassy in Athens. In many cases the USG declares who works for the CIA to the host government.
Do you think that she may have been "on the books" in the Human Resources office of CIA as covert, purely for pay differential purposes?