If it was just from the circuit loading, I would expect that the temperature of the conductor would be more uniform. There is a hot spot at the point of termination and I would expect to find a poor connection based on the picture.
Don,
We had an Industrial situation where a customers Inspector told them a breaker was running too hot and they sent a FLIR report. From the picture alone it looked like a real issue. Colors can be very deceiving, in this report the hot spot was "white" hot.
Unfortunately this was from about 10 years ago at a different job position so I no longer have access to the actual numbers or I would relate them.
We went out to the field and inspected, measured currents etc. Nothing was wrong. This breaker was loaded more heavily than others in the same panel but within ratings.
Once back in the lab I ran the same breaker type under normal load current and measured the temperature of the thermal element with a thermocouple. It was very, very hot ( wish I still had that report for actual numbers). Taking a FLIR of that test breaker looked just like the field report and nothing was of concern.
They were showing the very hot spot that was actually the thermal element in the breaker. This very hot element has a good thermal conduction path to the load wire termination. You will see the heat from the thermal overload travel some distance down the wire. In this case it was not about the wire heating directly due to load current but instead from the thermal element outward for a short distance. Looked very much like a loose terminal might but it was not a loose terminal.
I am not saying this case is the same. I am just saying more information is required than just a FLIR picture with relatively low temperatures being shown.
Again I wish I had access to the data. Going strictly from a very poor memory the picture shown here is much cooler than we measured.