I think an interesting concept here is how thinly traded Steem has been of late that these moves could be more common. If you look at the amount of volume on Bithumb you wouls be amazed on the way it trades at such a premium. However, I think this is due to the fact that only about 18-20% of liquid Steem is on exchanges and the the fact that most Steem remains staked which will be good for the long term.