This turned out to be a timed event in an area called "The Collapsing Vault", where I had two minutes to get to the end of the area and find whatever treasure lay within. I would like to mention that I am currently on nightmare and playing Solo. Despite my best efforts I could not finish the vault before it "collapsed"
With 10 seconds left on the timer before the vault "collapsed" I used a town portal to escape. Seconds later the quest showed in my log as "failed" and I went on about my buisness. I came back to town about 15-30 minutes later and noticed I had a town portal up, curious as to where it went I jumped in and was taken back to the "Collapsing Vault" that turned out to be very much still in-tact. I was able to explore the rest of the vault, although I found no special treasure that perhaps a quest would have placed there. However there were still rare mobs floating around.
Anyway, I just thought I should point this out. Im not sure if this is considered a bug because it was just a town portal, but I think the vault very much should have "collapsed" and my town portal should have been closed. I would note that after I failed the quest I was no longer able to take the original spawned quest portal in, as it was closed.