Advice needed!

So I trust my boyfriend 100% however he lives in a small town, that he grew up in. He dated this girl for 2 years on and off a little. Now they are friends. However, when we first stared dating she would say things to him lime "she is too young for you"(he is 8 1/2 years older than me) or "your not right together" yet she had a boyfriend at the time. This is my first relationship so I'm really not sure how I should feel about this. This weekend we were out and about and we saw her. He gave a small wave and we kept on walking. Should I be bothered by this? Should I be okay with it? I know he only talks to her about business related things.