Of course, for every seller there is a buyer. A 40,000 share block is quite large and probably is an institutional buyer.
I am very curious about the seller. Many of us believe this company has a great future and therefore a much higher price. I would hope the seller also believes this and is one of the large block holders, needs some cash, and 40,000 shares still leaves him plenty for the future. Otherwise ???
I too would assume the shares were picked up by an institutional buyer. In fact, it's my opinion that someone has been looking for some size and certain market makers activities as of late are indicative of such. Even as I type, you can note a certain market maker low offering trying to shake out some sellers while they bid the stock. Just doing their job trying to get their customers the best price.
Regarding why would anyone sell, know that there will always be sellers, in this stock and any other. I would not concern myself with the actions of others, focus on what you know. Remember there were also sellers at $1 in the past just prior to the shares running to almost $5. I would just not assume everyone who owns the stock is as educated as you and I might like to believe.
I think anyone selling here is merely doing the fund buyers and those of us who have been adding, a tremendous favor. One which I'm personally extremely grateful for.