How would you feel about your child(18 yr old) dating a 24 year old?

I (30f) am concerned that my daughter (18f) has started dating a 24 year old. She is in her final year at highschool. I know it's not a massive age gap, but it feels too much to me for their stages of life. She is 18, finishing high-school, doing her driver's license, and going on to do a certificate course in the next year. He is 24 and finishing his college degree and working in a full time job. <br><br>I am aware that a 6 year age gap isn't a massive difference, but I feel like they have different maturity levels and are in different stages of life which feels like a big power imbalance. Am I being overprotective as a mother or is it reasonable to have concerns?<br><br>Any advice?