Feature Requests Check a recent date on a statically generated site

I've some statically generated site being served by a simple web server.

Sometimes the batch process generating them doesn't work anymore and the pages remain non-fresh but correctly served, so for my updown check everything looks great.

I would love to have a way to specify some text with a date in the page (in a standardized way so that is easy for updown to parse it) and tell updown to fire an alarm if the date is not recent enough.