Yes. They would just do it in front of everyone and claim it was tactical. There's nothing tactical about it! It's literally "I'm saying something to my Master in front of you and you can't tell what it is!" Which was probably the point, but.... not tactical.

[See this deleted scene from RotS. If she's getting a little heated and putting on an unflattering voice it's because she's long reached the point where anything and everything the Traitor ever did is the worst thing ever.]

Just make it significant. Do it during a pause. If I nod I think it's a signal, and then if it actually isn't go make a face or something.