Remaining pages from old site are, in some cases, 304ing (not 301ing)

[henryhund]

Examples:

• https://www.aptible.com/blog/definitions.html
• https://www.aptible.com/blog/authors/gib.html (all authors seem to have this old page)
• https://www.aptible.com/blog/no-flash-no-problem.html

This is happening when I go directly to the above URLs. If I visit those URLs from a link, the 301 redirects properly. I'm not sure what might be causing this...