No shit.  I was describing this very thing to someone knowledgable in finance, who recently learned of bitcoins (and is now invested heavily).  I told him how bitcoins rose to $9 about 3 weeks ago, then started slipping back to 8, then to 7, stagnated, then slipped even further to like $5.20.  It was all based on miner sentiment apparently, because I was one of the ones who sold off during the slip.  I didn't want all of my effort to be worth $0.  So of course this led me to the conclusion that the market is controlled completely by miners, who are mostly dumb kids with free power in mom's basement or a dorm room, irrationally reinvesting most of their money into mining ("to combat difficulty rises" is the excuse often used), and then irrationally selling off.  While it might've been rational to sell off during the aforementioned slip in the market, the current selloffs are just foolish.  Sadly, the market seems to be dominated by said fools.  *sigh*

its just the natural ebb and flow of sentiment.  parabolic ramp with normal correction.   

Its just regular 'profit taking'.