Error headers: ap_headers_output_filter() after putting cache header in htaccess file

Receiving error: [debug] mod_headers.c(663): headers: ap_headers_output_filter()

after I included this within the htaccess file:

# 6 DAYS
<FilesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gi开发者_如何学Cf|js|css|swf)$">
Header set Cache-Control "max-age=518400, public"
</FilesMatch>

# 2 DAYS
<FilesMatch "\.(xml|txt)$">
Header set Cache-Control "max-age=172800, public, must-revalidate"
</FilesMatch>

# 2 HOURS
<FilesMatch "\.(html|htm)$">
Header set Cache-Control "max-age=7200, must-revalidate"
</FilesMatch>

Any help is appreciated as to what I could do to fix this?

Your configuration looks perfectly fine. You should just change LogLevel from debug to warn (or whatever your favorite level is).