It really isn't uncommon. The condition occurs either as a result of too much chemical used when he tissue culture batch was made or too much GA3 given the specimens when they were "pushed" to produce inflorescences.

You can read about it on this page on aroid pollination. Just look for the heading about the forced inducement of an inflorescence.

Here is a link that might be useful: Aroid pollination

Thanks! I thought I'd stumbled across something exceptional. I'll still pick it up if I see it again, just to observe the G3 effects for the heck of it, and because it's cheap, but at least now I won't be rushing out to grab it.