In "The Crucible" what was Mary Warren's explanation for leaving the house and going into Salem that day?

Since the first accusations were made in Reverend Parris's house, Mary has been a part of most of the proceedings in the courtroom.  So when Johh Proctor demands to know where she has been all day her response is that she is "an official of the court now", meaning, she has been given a title of "official" at the court, and is duty-bound to be there for the proceedings each day.  Also, she feels it it is "weighty work" that she does; for once, Mary Warren feels important, wanted, listened to, and brave.  So, she tells John that she will "be gone every day for some time."  However, once Elizabeth is arrested, she stays at home "strivin' with her soul", trying to get the true courage to go against Abigail and all of the other girls.