I am not sure we always need a retraining. Even that can potentially be done but putting it in a knowledge graph can be quick. We don't know the exact workings. I understand the shepherding logic you are explaining and I have felt the exact things when writing code recently because the best thing to do is often unique in coding circumstances. But a random phrase being repeated in 2 days has a much lower probability.

But is it really a random phrase? My point is that we have neuron activations, during the conversation you had the same inputs as the other person, unless you though about that phrase in the shower, if it was during the conversation you might have been lead to it, and the other person too.

Or it might be just pure chance, or might be that you are right, check your settings, in chtatgpt there is a check (activated by default ) that states you agree to help improving other conversations. I’m not sure the same is true in Claude.