In most States in this country there are statutes and court decisions requiring the owner of an easement to maintain the easement at his or her cost and not at the cost of the property owner.The degree of effort for maintenance of an easement by its owner typically depends upon the nature of the easement, its scope, its purpose and in your case a presumed roadway easement for access the terrain of the land.If the easement through your property is for general roadway purposes for access, most likely adding gravel to it by the neighbor to fill in pot holes and smooth out its surface would be part of the allowed maintenance and upkeep by the owner of the easement.