Today, I was sitting at a good vendor at floor 13. It had the Sunset Duster, Fiery Pepperbox, Faust, Ionized Salt Bomb and Cold Iron Carver recipes, which are all fairly commonly sought after for a nice price. I had a friend advertising ports down for me, and I was tabbed out of the game (un-fullscreened, switched spaces and was browsing forums). When I went to the game to fullscreen and see what was being said, I was ported back to Haven immediately upon fullscreen. Even as I had got no purchases or offers yet, I was about to make a deal, and I was saving the recipe vendor for my guildie who needed the Duster.
I was extremely disappointed.
I don't know what caused this, but I hope it gets fixed soon.
Additionally, it may be pertinent to note that I was dead and alone in my party on the floor. I was messing around with my Faust's charge's curse while standing on the health blocks, to see if I could die while standing on one. Turns out you can, by the way.