Specify Cache Validator

Have the plugin running and the fonts are loading locally – but I am now getting a “Specify a cache validator” error for the fonts where I didn’t get that with prior named version. Is this something I can tweak with a setting. The detail of GtMetrix says:

“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…”

Thank you!

The page I need help with: [log in to see the link]