It very well maybe a spike! I asked (last time I was at the greenhouse) about why Chosentetsu (Yoroidoushi) grew spikes from the tops of the fans. I guess it's not uncommon for them to do this. Once it spikes and blooms from the top of that particular fan, that fan will stop growing leaves. However, you will get new growth (new fans) elsewhere. So maybe it's the same with Aojiku Chosentetsu.
Also, Aojiku means "green axis". Chosentetsu is re-registered as Yoroidoushi, which means "dagger".
Tim, you got a pic of that spike?