There is apparently a problem with the Blog's safety certificate.

Ignore it.

Like all the so-called 'safe' schemes touted on the web, these certificates are more bother than they are worth.

This one's part of WordPress anyway, so has nothing to do with me, so I can't do anything about it if it decides to throw a flakey.

See what I mean about them being a waste of time? If they throw up a warning, everyone just clicks to ignore them.