After further research, I can only guess that it is a mutation, and will probably produce more nodes with 3 leaves or branches. It is hereditary and is a good thing for the most part, since it will naturally be more bushy; but will be shorter than the rest.
Had 2 of my plants throw a branch out with 3 nodes. I ended up waiting for them to mature a bit and took those nodes as cuttings. Those cuttings are now being mainlined. Check out the mainlining thread. If you're going to do any topping it might be something to consider.