Ditto on what Hoss said. I always seal gaps on all surfaces. Even small gaps can make planes hunt for trim and less responsive. I'd agree that aileron are the most important but while you got the tape out, you might as well seal the elevators and rudders. You can also use clear or colored iron on covering to seal the gaps. Only need to seal one side (I typically seal the bottom where it isn't seen as easily.) Just be sure the control surface can still move properly.