Parents, how would you respond to this? what would be your first thoughts?

if you had an 18 year old daughter (still living at home, pays for all of her own expenses except college, and you know she's not that reckless and crazy of a teen) and she came to you one day and said "i'm going to a three day music festival in a forest park four hours away from home with my boyfriend," what would be your first reaction? how would you respond? i'd like a general idea of parental concerns before i start talking to my parents about my planned trip, they're kinda overprotective/controlling, and i dont want to start an argument with them...