A WebmasterWorld reports finding that Google is showing the cache date in minutes.
Typically, Google shows a date and not a countdown in minutes as to when Googlebot last retrieved the page. Here is an example of Google showing the date and not in minutes:
The boxed in date is what I am talking about.
Here is an example that I was able to reproduce on http://126.96.36.199 showing the cache date in last minutes.
This appears to be a new way of Google displaying this information.
Forum discussion at WebmasterWorld.