Yeah, sometimes you can just get unlucky with the rush gods, even if you have a good deck that practically auto-wins vs them.
I brought it up, though, because it feels like against Ferox you'd want 3 or 4 shields for better consistency / odds of winning / blunting Ferox's rush. I know that for one of the FGs which loses to grav shield, the recommended Oracle decks pack 4 shields.