Rare Obsidian Portal

This portal was found floating above an ocean about 5 minutes walk from my spawn. It never used to be there. It looked like an odd upside down T when I saw it from a distance. I went to check it out. Cool huh?
I've gone through it. And it takes me to the Nether. Strangely it makes me appear at my own gate that I created earlier. Going back through the portal again sends me to the other end of my gate, safe at home. Meaning I now have a quick way from going from the middle of the ocean back to the safety of my base.
I originally thought it was the secret beta update. Turns out its just another rare thing that I stumbled over. Dang. Oh well. I feel like an idiot. Cheers for smoothing that out before I looked like an idiot on the internet Matt.