Formatting error
Depending on the number of tiles and their sizes determines if a gutter/border is added to the left and right sides of the iOS app or not. Ideally this would be consistently displayed or not (our preference is that is isn't) - or for this to be optionally turned off or on.
The way tiles are arranged in the home page is complicated - as we cannot know ahead of time which combination of roles and tags any one user may have - nor can we predict what devices they may use. The change in the "gutter" on the sides of the app is a natural consequence of this.
This behavior can be affected by the app/profile settings in App Builder, as you can set a min/max number of column, and tile sizes.