Cached image question?

Hank Brennan made a comment today attempting to rebut part of Green's affidavit about the image loading for the prompted search how long to digest food. He said the image was a cached image and thus did not require service to load.

My question is wouldn't this therefore necessitate that a search was made prior to the 630am time frame when there was service in order to cache the image for the 630 search?

Would there be a way to find out when the image was cached?