How does the body itself feel?
Squishy? If squishy, it might still be rot - rot does not always get the roots first unfortunately....
Not sure if you are in Arizona, but I think you are, did the plant get any of the rain from a couple of weeks ago? If so, too little water would seem impossible, but it has been quite hot already for periods of time, so it could just be a little too little water.
I am already watering most of my potted plants that get a lot of sun once every two weeks, because they were looking like they needed it and then it rained of course...
