Thanks guys for all the responses!
It sounds like it is really sensitive to cool weather and goes dormant easily. I found this blog post where the same thing happened to their plant in fall, but they kept the pot until the following spring (in St. Petersburg, FL) and the "dead" tan twigs sprouted new leaves the next year around April/May.
Surprisingly, I found it at a local nursery.
Not so surprisingly, no one really knew anything about it.
I think I'll avoid putting it in a mixed container and give it a pot of its own so I can bring it in easily when the cold arrives.
(and pray the nasty Kudzu Bugs don't find it interesting. Eeek!)