/blog Redirect Issue

I’m having a strange issue. On my site, /blog redirects to a seemingly random specific post (/12706 to be exact — my permalink structure is /%post_id%). I cannot figure out what is causing this. I do not have any hard-coded redirects (i.e., .htaccess, etc.). I double-checked this by setting that specific post to draft status, which causes /blog to redirect to a different post that was created on the same day. Both my WordPress address and my site address are the same thing (the root domain of my site with no sub-directory). Other unused sub-directories (/fred or whatever) are properly returning the 404 page.

Any ideas why?

Thanks,
Mike