What may have changed is she and the other reporter didnt consider the releases that the special prosecutor got Rove and Libby to sign as being true releases. The guy at Time received verbal release from Rove stating it was not coerced. Probably same now with Scotter Libby. Only thing that is strange is why now rather than three months ago?
the "2nd release" that Cooper got from Rove was all publicity - in fact, it was a mistake by Rove's lawyer - it allowed Cooper to grandstand in front of the courthouse, it meant nothing legally.
why would Scooter Libby and his lawyer do exactly the same thing now, giving a legally meaningless "2nd release" to Miller?
Simply not credible. No one would sit in jail, even in Alexandria, for three months simply because she didn't feel like picking up the phone and calling Libby to hear him say the waiver directly.
She has decided for reasons of her own that right now is the best time for her to come out and face Fitzgerald's questions, and is just using this story about the waiver to fool people into thinking otherwise.
She may have been pursuing other tacks during this time, for example seeing if powerful republican friends could somehow help her out, maybe public outrage would somehow come to her rescue, etc., and has now finally concluded that none these other possibilities will pan out.
Or perhaps she has finally managed to figure out through sources just what Fitzgerald knows, and armed with that knowledge will take her chances with the grand jury hoping to employ some deft Clintonisms while continuing to protect whatever it is she doesn't want to reveal.