My mother was the same way. After my first date she made me feel such a dirty horrible guilt for going out with the boy. She implied the things she told you, but to my face.

I want you to know that letting your daughter have a date like this one at 14 is a great thing you have done for her. A positive first experience where you were not only her confidant, but support will lay groundwork for her comming to you in the future with any issues she may have when it comes to relationships. Having noone to turn to because: Im such a whore for going out with these boys - aka moms method, would be a terrible thing. It was for me.

Stay cool dad, you did well. Moms are not always right.