No, very plausible given AI companies want/need user data to train their next models. As stated in the paper, it is probable the researcher sessions were used for training the model used

"I asked whether the model had been trained on, or had access to, our sessions in Codex, into which we had been putting all our drafts for the whole of this project. I was told the model did not look up user data. I asked again, about training, and I did not get an answer."