The reason I suggest Zygopetalum over Spathoglottis is that Zygs produce a flower spike before they form a pseudobulb, whereas, I believe, Spathoglottis form spikes after they form p-bulbs. In your photo, it seems the spike is coming from a new growth that doesn't have a p-bulb yet.
Also, have you been able to find photos of Zyg p-bulbs and Spathoglottis p-bulbs? The Spathoglottis p-bulbs I've seen are usually shorter and rounder than flatter Zyg p-bulbs.
And thirdly, is your orchid growing in a bark mixture? Around here, at least, the Spath's I've seen are growing in soil.
I would not call myself an expert, but that is my reasoning. Time will tell one way or the other. There are some really striking Zygapetalum varieties and hybrids. Whatever you've got, I think you were smart to snatch it up!