Hello 
We've been seeing these errors somewhat frequently lately. Some have suggested that they can be related to a nameserver problem. I'm going to ask someone for their specific input though because I want a definitive answer.
I elevated this to the LE staff once I had confirmed it was an LE server issue and nothing specifically certbot. This topic says it all.
Sorry for pinging you all, but it has now reached outbreak level. Here are several other recent occurrences.