Page and post_name Conflicts

Hi,

I’m trying to get this URL path to work for pages:

mysite.com/issues/2013/january

I created a page called issues, a child page called 2013, and a grandchild page called January. WP is saying this is the link structure to use:

mysite.somc/issues/2013-2/january

When I change the 2013 page slug to “2013” WP changes it to “2013-2”. However, I don’t have another page, post, or category with the slug “2013”. I’ve looked in the wp_posts, wp_terms, and other tables, as well as searched Posts, Categories, and Pages to find where there might be a conflict, if that’s the issue.

I did find this topic but it didn’t help/work:

http://wordpress.org/support/topic/cant-have-a-page_name-with-just-numbers

Any ideas how I could trace this issue where WP rewrites my slug to append a “-2”? What might trigger this behavior besides conflicting slugs? And how could I definitively determine whether or not I have conflicting slugs?

Thank in advance for any ideas!

Update: My permalinks are set to http://mysite.com/sample-post/ if that’s useful data.