Thanks for everybody's replies. I do understand that gap has nothing really to do with flutter.
Hmmm I am not sure about this statement. If you have a gap say 4 mm and mylar hinges then you have slop. It will allow the control surface to move up and down at the leading edge even if the control linkage is stiff. I have no evidence to support my SWAG on this subject but I would still not pass an aircraft as fit to fly with big gaps.
Flutter can destroy an aircraft in an eyeblink.