You are 16 and he is 15. By the time you are twenty, you will have both developed yourselves a great deal and may even find that your experiences have put you into different spheres. The age difference is not relevant (My OH is three years older than me!)
You really should not worry about it - concentrate on developing yourself to be the person you want to be and let him do the same. If you meet up with him then and the chemistry works great - otherwise you may even meet up and find yourself asking "Who the H*LL is that? What a lucky escape!" Remeber very very few of us end up with our first or even second love!