She needs no second invitation. And her reaction tells us of conversion. Though not yet baptised, she starts doing all the things that a Christ follower does. She changes her life, she has a new vision and she shares her joy. John rarely slips in an incidental comment.
Every word counts.
Having been weary at the well, we see a new energy enter this woman. As she believes in Jesus as the eternal water giver, she has a new spring in her step. The disciples come back to be with Jesus and she is off. She is obeying Jesus already. It's not the well water but the Jesus water that helps us live.