The only odd thing I've seen and heard about is that a nearly mature bulb may sprout a new bulb from the top. But that's very very rare.
Blow. I have an oncidium ('Munsterland Stern', which is not a registered grex...) which I was going to take to my orchid society auction in Jan to make some space. I might have to keep it now. It has three pulbs one on top of the other!