waivers by implication can sometimes extend beyond the matter *24 actually revealed. See, e.g., In re Grand Jury Proceeding, 219 F.3d at 182-83; Sedco Intl, S.A. Cory, 683 F.2d 1201, 1206 (8th Cir.19 ). Such waivers are almost invariably premised on fairness concerns. See von Bulow, 828 F.2d at 101-