It reeks of illicit cash grab to me, just like what happened with MTgox a few weeks ago, but maybe this time it's laundered?
Sure maybe, who knows, but I really don't think so.
There are plenty of miners who got in before Bitcoin was at even $5.
Somebody had a large ~10,000 coin 'buy wall' up at ~$15 yesterday.
The point of a 'buy wall' is not to buy 10,000 coins at $15, it's to force people who want to buy coins to pay more than $15 and help drive up the price.
However, it fails if somebody says 'wow, I can sell 10,000 coins for $15, that's $150,000...I can't leave that money on the table, I just have to do it!.' Then the guy with the 10,000 coin 'buy wall' now has bought 10,000 coins for $15 each.
Maybe it was one somebody who was an early adopter and has way more coins still. For that kind of guy, taking the cash when the opportunity presented itself while still having a lot of bitcoins is a great idea. Or maybe a speculator was able to get completely out. Who knows.
I don't know, either way it doesn't seem all that...unexpected, wild, crazy, suspicious or whatever to me.