Glad to see that it stopped after you refreshed. But if it does happen again I think that I have found out as to what your problem may very well be. After opening Opera, to find out if I too get what you were experiencing and found out I was not, I have found that I'm using version 12.11, and when I saw it wanted me to go to 12.12, your present version, I said no. But I would not worry because browsers are like that. The folks at another forum I participate in have to use Opera or another browser because Firefox interferes with the software at the forum, which makes us unable to use the quick buttons in posting areas such as: quote, images, and smilies useless unless we type them out.
If you continue having that trouble you may wish to use another browser such as Firefox or IE. I would let the different browsers, and the different forum software out there, figure it out and get on with enjoying your life.