I dont know what you mean by the 30 btc comment.
Ok, say I want to sell 4000 BTC for at least $115. I can't do it in one big swoop, otherwise I'll just trigger a panic sell.
Instead, I wait for the buy bids to creep up and sell to them, while making sure I don't sell lower than $115.
Obviously it works as well for buying.
All I'm saying is that I've witnessed someone(s) cashing out slowly.