Well, since one generally only stops a bike when moving forward, the rotor should move, once, to its resting place on the first stop and not move any more unless you reverse the action. Maybe this is a non-issue. Unless you have reason to be concerned about it coming loose (which seems unlikely) I would not be too concerned.

Like the old joke, the guy tells his doctor "It hurts when I do this", doc's responds, "Don't do that".