Please allow me to begin by suggesting that you make absolutely sure you understand the laws, ALL the laws, regarding open carry in your State and any pertinent (if they apply) local ordinances where you intend to carry.
Do not allow yourself to be intimidated by either police officers who do not have any legal reason to harass you.. (if they have a legal reason to harass you then it is you who screwed up not knowing the laws).. or by any citizens who just don't like to see legally carried guns in plain sight. If you are not doing anything wrong (or illegal) please do not let some jerk try to guilt you into thinking you are doing something wrong.
Now... let me also very strongly.. extremely strongly... damn near shout in your ear ... suggest.. following the link below to discover the laws for Maine from people who already open carry in Maine.
Good luck to you...