JMs will often 'flame out' when they are in pots. I've seen it frequently at retail nurseries and even have a 13 foot tall Higasayama in my yard that 'flamed out' (i.e., all the leaves curled and went brown suddenly) - I bought it when it produced a second flush.
It could be any number of things associated with getting it to Sedona in a pot. Moreover, this is about the time of year that it should be dropping leaves anyway. Many red-leafed JMs make no color change for fall - leaves just wither and fall off, maybe turning brown first. I don't think there is anything to worry about as long as there are buds at the bases of those brown leaves.
The primary fungal issue is nectria. At this time of year, little orange fruiting bodies should be visible on the bark toward the base of the twigs with the leaves that are 'flaming out'. Since the OP doesn't mention any 'orange stuff' I am doubting that it is an issue. But, if there is orange stuff and/of a bunch of orange speckles, cut off the affected branches well below where the orange fruiting bodies are seen and promptly dispose of the affected branches. Thoroughly sterilize your pruner with isopropyl alcohol or a bleach solution (quarter cup per gallon concentration) after every cut. Nectria is very 'contagious'; the hyphae extend inches below (toward the roots) the area of the fruiting bodies.