<<Disclaimer: Verify this information before applying it to your situation.>>

I believe the correct answer is shaoxing rice wine, and similar
Chinese wines, often contain gluten. The website

http://ocean.wxuli.edu.cn/wine/u3-2.htm

has information on the brewing process.

In general, I would not trust the label to be entirely accurate.
I've seen many things in oriental grocery stores that clearly
did _not_ list all ingredients. In an extreme case, my son---who
is allergic to peanuts---ate a bite of a sweet that did not
list peanuts as an ingredient, but definitely contained
ground peanuts. I would not trust the U.S. distributor
to know the precise ingredients either.