A second exposure confirms that my recent
finding was not a camera error, but a variable star.

ISO 6400 1s f/5.6
50 light / 10 dark
Bortle 8

variable.gif: 
All of my pictures of this star. You should be
able to see the star changing in brightness.

closer.gif:
In case the first one is too small, this
compares two shots, showing that the star
clearly dimmed in the later one.

I scoured tons of star catalogs, and I could only find one
source documenting this star:
http://astro.corlan.net/stars/OPH/SV-OPH.html

It's right beside Barnard's star, a common target.
Surely this star should be more popular...