No, as long as it is not loaded. If you do get stopped and the police harrass you, call your parent's and hand the officer the phone. Carrying a note if you are under 18 years old is a good idea. Always be polite.
Freedom is not free. The best of us always leave too soon.
It is illegal to have a loaded or rifle in any kind of motorized vehicle. Anyone can have a rifle or shotgun in NH, regardless or where they are a resident. However, no private citizen can have a loaded rifle or shotgun in their vehicle. Military and Law enforcement are exempt from this law.