Here's the picture. The spots have a dark ring around them and a kind of yellow/brown center. I haven't dissected one yet. I'm not sure if they are spreading (in number or size) but now I have this photo to compare later.
Galeopetalum - a member of the zygopetalum family. Zygos seem pretty prone to black spotting - usually on the leaves. I have a few, but they don't suffer - possibly because I can grow them cool and humid. I think it could be just the usual spotting but this time on the pseudobulb - I don't think there is much you can do about it - it the plant seems otherwise healthy I would not worry.