I would recommend to use facing pages. Because this is the only way to be sure that all pages are moving together when the size of the back/spine changes.
That did it! Now when I change the spine width, the front page stays adjacent. Funny, both Eugene's instructions and Nigel French's instructions (from the Linda.com tutorial linked in this thread) said to turn off facing pages and had you butting up the front page manually after changing the spine width. Maybe this is something that InDesigned changed at some point.