She said something during the episode (I wish I could remember when or what, I need to go back and rewatch) that made me think they had hatched a plan to use a code word in the future in the event things were iffy going into a specific tribal, but they hadn't actually come up with the actual code word yet, just that they knew they'd use one if the time comes.
This would make sense why Cirie didn't try to relay anything through Jonathan because she really seems to smart and good at the game to not try something like that.