G`day All
Cuppa to answer your question, it`s exactly what we want, that is for the cups to move out then when they return the agitation of the fluid drags the little air that is left in the cyl, out. One other way is to open the bleeder then stomp hard on the pedal shut the bleeder release the pedal SLOWLY and repeat as necessary.
This works ok on the rear brakes of the early MINI`s where the bleeder was placed in the bottom of the cyl.
Some times English engineering left something to be desired.