North Carolina’s highest court is now considering whether the legislature’s decision 10 years ago to begin charging some retired state government workers and teachers a premium for health insurance violated an agreement the state made with those workers. The justices heard arguments Monday but didn't immediately rule. Their decision could affect hundreds of thousands of retirees and the state with premium refunds and future expenses. Retirees argue the state was contractually obligated to offer premium-free benefits under a plan in which they paid 20 percent of their co-insurance. State attorneys say there was never a contract, and that lawmakers have adjusted insurance benefits often.