We're dealing with two different definitions of "covert".
The rule is "once a NOC, always a NOC".
Thus, by the CIA's internal operational standards, Plame was "covert" -- but inactive.
But the 1982 IIPA relies on a specific legal definition of "covert" -- and Plame did not meet that standard.
Since she was on the operational side of CIA, her employment would be accurately described as "classified".
As examples:
Top Secret
Secret
Confidential
For Official Use Only
Restricted
NOFORN(Not For Foreign Release)
Sensitive
Unclassified
I doubt her current/last job title at the CIA working as an analyst was classified as anything but Unclassified.
Plame may work with classified information above Unclassified, but that does not make the knowledge of her working at Langley a secret.