After a short while I went to push on the midrange cone to see if it might be rubbing on a potentially off-center tweeter, but was surprised that the midrange cone was very hot. The midrange driver has a voice coil wound on an aluminum former bonded to an aluminum cone. This gives quite a good heat transfer from coil to cone.
I let it cool down, and repeated the experiment. Same result. In just a matter of 10-15 seconds the cone became very hot.
This is a lot of power being dissipated in the driver. On music I have never noticed that cone getting warm, despite playing at loud levels even in show conditions.