I do see this happen often, though. Ex. - Someone wants to buy 2,000,000 shares at say .0037 so the MM has to sell 2,000,000 shares. Now, the MM would like to cover lower than .0037. If the demand is not overwhelming, the MM will probably be able to match orders in such a way so as to get the price below. They would like the price to be as low as possible within reason of the trading range and overall volume.
Often after a little buying, price drops. After a little selling, price rises. I see it constantly.