Interesting that you have chosen <10 days for auto renewal
Issued certificates last for 90 days, and are automatically renewed when there is under 10 days remaining until expiry.
As today I got the following from Let’s Encrypt Bot
Your certificate (or certificates) for the names listed below will expire in 19 days (on 13 Feb 20 16:44 +0000). Please make sure to renew your certificate before then, or visitors to your website will encounter errors.
We recommend renewing certificates automatically when they have a third of their
total lifetime left. For Let’s Encrypt’s current 90-day certificates, that means
renewing 30 days before expiration. See
Integration Guide - Let's Encrypt for details.