Home tab defaults to a post, not default /blog/

This is strange, I published a new post last night and since then, the "Home" tab and the default URL for the blog go to the URL of the recent post.

Blog Default: http://www.theinternetbook.com/blog/

New default URL: http://www.theinternetbook.com/blog/...c-to-a-website

Using Atahualpa 3.6.4 and I made no other changes to the theme, menu, etc. Any idea how to correct this and why it happened?

Thanks,

Tom