But they were... as a child I remember reading about Erik the red who founded the first settlement in Greenland and whose son Luke or Lief made trips to what they called Vinland
The Vinland landings and artifacts have all been further north than Maine (in Newfoundland). So finding Norse artifacts in Maine means either they also traveled to Maine or some of their things got traded/taken south by someone.
https://en.m.wikipedia.org/wiki/Leif_Erikson