auto-numbering error

One of my documents has a glitch with the auto-numbering.  I have headings and subheading set up through paragraph styles with auto-numbering.  Everywhere in the document the numbering works just fine.  But there's one spread where it just won't work properly.

Image "AN1" shows the problem.  The heading is 4.2, but the following subheading is 4.1-1.  The second page is also 4.1-X (image "AN2").  It's not until the following spread that it correctly changes to 4.2-X.

If I move the text box on the first page to a very specific point to the right it will change to 4.2-X (image "AN3").

What in the world is going on?  I have no problems anywhere else in the document.  I've tried deleting and recreating the text boxes, changing the style and changing it back again.  Nothing fixes it.  Does anyone out there have any ideas about what's going on?