I don't believe there is anything in the papers that says she was covert. If there had been, he would have filed an indictment on the initial charge. Did you see something in the papers about the GJ saying she was covert?
It's on page 3 of the indictment:
"At all relevant times from January 1, 2002 through July 2003, Valerie Wilson was employed by the CIA, and her employment status was classified. Prior to July 14, 2003, Valerie Wilson's affiliation with the CIA was not common knowledge outside the intelligence community."