Somebody has definitely nicked it, mine got nicked (again) on Wednesday.
I had one go missing a few months ago, despite the fact that it had my address painted on all 4 sides of it. I then 'aquired' another one and put my house number on that one. Whilst I've been using the new one, my old one has re-appeared every week, still clearly displaying my address! Who on earth would carry on using a bin that clearly isn't theirs, they could at least have sanded my address off!!
Anyway, my new bin has disappeared this week so if my old one is there next week, I'm re-claiming it!