Hey ya, I´m getting this as my LAST error on fpt.pingdom.com and just because I like a 100/100 rating, I´m interested how I could get rid of this?
"The following resources are missing a cache validator. Resources that do not specify a cache validator cannot be refreshed efficiently. Specify a Last-Modified or ETag header to enable cache validation for the following resources:"
Three Autoptimize .php file links.