The opposite broker was at lunch or half asleep. Your broker comes up to him and sys what you have in Dec, it's one guy handling all the back months, and he has like three limits in his hand so he just says sold so he can go back to doing the crossword or harassing a female clerk or whatever. Runner brings the order back to the desk, the clerk is calling it in and he notices the price looks funny. He walks back to the pit himself, muttering about the wise guy who has to trade the out months when no one is even in the pit, bitches to the broker, the broker has to go find the broker holding the back months, bust the trade, take down the print, and then scare up a local who wants to make a market in a back month. That guy makes 3 or 4 ticks by quoting a wide market to your broker. The poor schlep will probably have that trade in his account until the next roll, maybe this december. He puts on a front month against it or whatever he's already got going that day. That's probably what happened. Nothing too sinister. You should realize that the locals ARE the little guys most of the time