Neat! I have some tiny patches live moss in my terrs but, as you noted, they are very slow to grow. The most exuberant moss growth in is my "sealed" terr. Unfortunately as the humidity is about 100% in that terr, the shock of being brought into an environment of signficantly lower humidity is traumatic for just about any plant and generally lethal for the mosses it seems.
It will be interesting to see how your moss survives in the long term. (Wonder if it will require a cool dormancy to remain healthy)