This probably isn't the best time for health insurers to admit their utter incompetence in handling their most important role under the reform, which is keeping a lid on healthcare costs. But that admission underlies a couple of lawsuits filed by Aetna and United Healthcare earlier this year, alleging that a Northern California chain of small surgical clinics fraudulently overcharged them tens of millions of dollars by counting on the insurers being asleep at the cost-control switch.