Some LEOs will not be aware of the law and will try to tell you that you have to be 21 to have a weapon. They tried to tell my neice this when she called the police regarding a neighbor verbally threating her (neice was 20 yo). Even if they know the law they will often try to mislead or misinform you.
Educate yourself, carry responsibly and carry safely.
Usual disclaimer applies...I'm not a lawyer nor do I play one on TV. I'm a guy on the internet giving you advice. Take it for what it's worth and do your own research. The last thing your defense lawyer wants to hear is that, as you were being arrested for something you stated "But, Officer, some guy on the interwebz told be I could."