Some of the oncidiums, like the yellow "dancing lady" hybrids, (especially those with varicosum in them) can take "forever" to complete their branching and bloom. (Especially when the grower is anxious for an end result!) Did you have this plant the last time it spiked and bloomed to see its growth habit? Last summer I had one that I'd estimate ended up between 4 to 4 1/2 feet tall before the branches were extended and flowers starting opening...I think it took 6 weeks or more if I recall... I'd wait it out and see...you might end up with a huge display?