Gee, wonder why?
But the other reporter said the source had released him. Presumably this is the same person.
She doesn't know who the source is, because she made it all up.
She can't just make up a name, because she might get it wrong and risk a perjury rap.
She can't ask the other reporter because that would probably be an obstruction of justice rap.
Enjoy your Summer, Judith
Please see my #56. She didn't make up a source and the grand jury knows exactly who it is (plus he/she has waived the confidentiality).
But it ain't. Just a hunch :)