I don't think age should be much of an issue. Yes, as others have said, you will be a different person in 10 years, but so what? What the real issue here is your living in different states.
If you're interested in him and in pursuing this relationship, just do it. Don't think about it so much. See if he wants you to come for a weekend visit.
Life is so short and you should enjoy yourself while you can. I know you're only 19 so you have many more years ahead of you than I do, but really - take every opportunity to have a fulfilling life.
We've all been hurt in relationships over the years, so just realize this might happen to you, too. It's a part of the whole cycle and very difficult to avoid. And it may or may not happen with you.
Have fun, take the plunge, and good luck to you.