Wait till her friends leave and approach her.

Still in shock from what just happened, you think to yourself "Did she just give me that little show on purpose? Hopefully her friends will leave soon and and I can muster up the courage to find out"

Just as you finish your thought her friends say goodbye and head off into the school.. Bethany is about to walk away too when you call her over, "Hey Bethany, can I talk to you a second?". She stops and turns around, looking straight as you as she walks your way. "Whats up, John? Make it quick we need to head to class..", she says as she comes to stand in front of you.