reed flutter?

Reed flutter you can usually hear if chronic sounds, well. . . like something fluttering. It is highly unlikely reeds designed for your bike are so far out of their design range they will flutter. This usually only happens when you radically change the engine or bend the stops back of steel reeds.

If they are sealing well then should be fine.

Sounds rich, but that is a throw away comment. Obviously do the simple stuff first. Check for airleaks, clean or new filter, new spark plug & cap.