i don't think age should matter. anyhoos, i went out with a guy without my parents knowledge because i knew they would be against it. but they probably figured out on their own (frequent phone calls, mushy gifts give it all away)- however, they didn't say anything about it, because they trust me and know that i won't do anything bad. (i come home when they tell me too, i don't drink/smoke, etc).
so, i guess the best thing to do would be to gain their trust? invite him over to meet your parents. show them what a great guy he is. hang out with him in groups.. give ur parents a contact number whenever you go out with him. stuff like that... hope all goes well.
cheers~