When Roberta Lane went to her local hospital emergency room, where the doctors she's seen for years practice, she was shocked to find out her insurance wouldn't cover treatment. The Auburn resident had bought a plan on the Affordable Care Act exchange through Anthem Blue Cross and Blue Shield, unaware that the hospital was one of the six excluded in the insurer's "narrow network," Lane wrote to lawmakers last month. Unable to immediately transfer to another hospital, she spent several days in Central Maine Medical Center worrying about how she'd pay for the mounting costs.