The only thing that maybe makes sense is a margin call. I once had a margin call from ETRADE. I was too slow to react so they just went into my account and sold part of my latest position for whatever they could get. Luckily it wasn't too many shares, but I was pissed because it went for the bid on a large spread. In any event, this 1M trade could have cost that guy a pretty potential penny. Sucks!
As far as Rocketstocks is concerned, just another malcontent;)