Finale can create hidden notes in order to play back some ornaments like trills, tremolos, and rolls. These hidden notes may appear grey on the screen after working with one of the TGTools or after applying Human Playback. These grey notes will not print out but you can always turn off the display by unchecking Show > Hidden Notes and Rests in the View menu. 

 

Displays grey hidden 64th notes attached to a trill and mordent