debacque, Did you know that sealing a hinge gap can CREATE flutter?

Flutter is caused by aerodynamic forces. Sealing a closed hinge gap MIGHT reduce it, but then, opening a sealed hinge gap might reduce it also.

By the same token, doing either just might do nothing. this is more likely the case.

Do not rely on the hinge gap to affect flutter. Keep your linkages tight, and use servos that are appropriate for the application and you won't have to worry about it.