I had aileron flutter with a Tiger 3 (40 sized low wing). I could hear it flutter quite clearly but was able to bring the plane down without incident. Others in our club have had the same problem with this particular model and solve it by replacing the single servo (with longish linkages) for the ailerons with a separate servo for each aileron.

An old timer at the field who heard my aileron flutter applied a long strip of cellophane tape along the forward edge of the aileron and the flutter didn't come back. Unfortunately I crashed the plane only a couple of flights later due to a completely different reason.

I have another Tiger 3 now and have fitted dual servos and it has no aileron flutter although I've only flown it a few times.