This was stage two.
Stage one was with the recruiting agency, and they were more attuned to the interview.
This was the "real" interview with the company, and the guy just didn't seem that attuned to the interview. He asked a series of questions, and I got them right but missed one. That was it for me.
There are not many Plotly developers, so finding me seemed like a great fit. This went off the rails when I told him I saved my company $50K with a technical solution and was able to avoid the licensed version and use the free one.
If I would have lied I would have gotten the offer.