Lyric discussion by Duluth_13 

Cover art for California lyrics by Mason Jennings

While i can see the reference to acting the rest of the song seems so sincere that i have to question whether or not he means that he is a leading man as in the best. he does say

"Don't you know baby I'm a leading man I dig down deep when I say I love you And I can hold my own with the best of them I guarantee you, you will never see nothing like this again"

it could mean that he is one of a kind and if she leaves him she will never have another man that is as good. or atleast they will be hard to find