It's probably the ducts running under the console to the rear control in the second row. But if you are using A/C which is about what everyone is doing now, does it still get hot?
IIRC, in the winter months, when I put my portable mug in the cup holder area, I remember it being warm due to the heat (not of the mug but heater).
Um, no. There are no ducts running under the console from the front heater to the console vents. The console contains a completely separate heater core, AC condenser, and fan to provide heat and A/C to the rear area. That's why the console is so massive yet not very deep.
If you're wonder how I know this, I have the factory service manual and it's covered in there.