You are all consenting adults. I don't see a problem. There could be some differences in maturity, and that's no one's fault; it just happens when one partner happens to have more life experience than the other. However, age is no guarantee of maturity, wisdom, experience, etc. When it is, empathy can go a long way in bridging the age gap. Understanding where your partner is coming from and that their experiences are not your own is important whether the age difference is ten years or ten days.
Anyway, I'm 23 and my primary and secondary lovers are both in their early 30s, so I've spent some time thinking about this, too.