Pages not respecting custom Cache-Control header

Any ideas on why Page's wouldn't be respecting a custom cache-control header for CSS files?

I have this in my _headers file:

/*.css
   Cache-Control: public, max-age=0, must-revalidate

/*.css
   Cache-Control: public, max-age=0, must-revalidate

/*.css
   Cache-Control: public, max-age=0, must-revalidate

/*.css
   Cache-Control: public, max-age=0, must-revalidate

Yet, CSS files are being served with

Cache-Control: public, max-age=14400, must-revalidate

Cache-Control: public, max-age=14400, must-revalidate

Cache-Control: public, max-age=14400, must-revalidate

Cache-Control: public, max-age=14400, must-revalidate

Any ideas?