It sounded like they weren't training but they were trying to figure out what gpt-5 structure, tooling, and training data will look like

4 months is an eternity in AI right now. I would be shocked if they are not training a new GPT (at least in experimentation/research mode, if not full pretraining) - else what are their GPUs spinning on? That is not a capital investment you just let sit idle.

But I concede that I don’t have any concrete proof so I should modulate my certainty of tone.

This was in June and they've continued to improve GPT-4 since then. Surely they're building on GPT-4 to learn how to approach GPT-5