Hi Michelle -- Unfortunately, a map or some other content in your story must still not be public because I still get a login screen when I try to open it.
You can check what might be causing this if you scan your story using our My Stories tool. It will let you know if something isn't shared in the same way as your story.
http://storymaps.arcgis.com/en/my-stories/
Owen
Owen Evans
Lead Product Engineer | StoryMaps