Yes, this has happened to me many times. The only correlation I ever had a hunch at was perhaps a long delay before hitting the arrow (like where I had opened

Yes, this has happened to me many times. The only correlation I ever had a hunch at was perhaps a long delay before hitting the arrow (like where I had opened a new tab and gotten to it later). Reloading the page (which at that point is the previous page) gets rid of the problem. Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.5) Gecko/2009010220 Gentoo Firefox/3.0.5