Sloppy linkage will cause flutter, but gap is not the cause of flutter at all, it will cause your surfaces to be less effective, no doubt about that.

Having a gap only changes the frequency that excites flutter mode; sealing the gaps in some cases can actually induce flutter over an open gap. The only real way to protect your aircraft from flutter is to: 1 mass balance the surface, 2 use servos that will handle the loads, and 3 the likage has to be tight, and slop free, its that simple...

Bob