Gary,

The ailerons move due to lift loads on the control surface.  It is the rear part of the wing and produces lift. Slop or flex in the control system allows it to move. On most airfoils this upward movement can increment drag as a smaller surface is now producing lift (wing now minus ailerons this also normally negatively affects lift distribution) thereby increasing the induced drag because the wing is operating at a slightly higher angle of attack to equal the aircraft’s weight.  Additionally it can mess up chordwise lift distribution by producing an adverse pressure gradient.

Jack Webb