I am not "burned," this happened a decade ago and I'm over it. I shared my story because I thought it was relevant to OP's situation.

Yes, my choice was odd. Because i was young, immature  and dumb. He, however, knew what he was doing. That's the point. Major maturity and power imbalances are not a good thing.

Perhaps this girl is super mature. If the relationship is healthy then good for them. I'm just saying OP is right to be concerned.