Moved from "Parasitica" (parasitic Apocrita).
Thanks! It must be a hyperparasitoid, because the gall had been in a sealed bag since Dec. 30 and this is the first time I noticed it--I've been checking the bag more or less daily, but had just been away for three days, so I think it emerged and died during that time. I didn't see a new exit hole, so I think it either emerged from the torymid's exit hole or maybe emerged at the base of the gall where it would be hard to discern a tiny hole. It's possible, also, that it emerged at the same time that the torymid did, and took me a whole month to notice, but I think this is very unlikely.
There aren't any encyrtids listed here, but I suppose a hyperparisitoid would only be listed under the parasitoid it's parasitizing, rather than under the parasitoid's host.

These particular galls are known to secrete a sugary substance that may have attracted the encrytid looking for some quick energy, but this is just speculation at this point. There are recorded encyrtid hyperparasitoids of other chalcids such as pteromalids or other encyrtids through different hosts. Did you find any other insects in the bag or gall?

See reference here.