John Mueller of Google said on Twitter that the date of the cache displayed in Google is not indicative of the crawl rate or how recently your page was crawled.

Here are the set of tweets:

This is not 100% new, as we know Google said they do not update the cache date on each crawl. John Mueller said back then, “In general, we do not always update the cached page every time that we crawl a page.” He added, that this is especially the case “when the page does not significantly change, we may opt to just keeping the old date on it.”

So if your cache dates are a bit dated, I would not assume Google is crawling less.

Forum discussion at Twitter.