yes, the bonus on the vitality is given by the attribute building in the outpost in the respective province, therefore, if you are going to a province that has the bonus on the attributes, from a province that hasn't it, your vitality point will be increased (as well as your health points), but the current amount of health will remain unchanged, so you must heal mercs and you for reach the maximum amount of health reachable in that province with the attribute building in the respective outpost.