Well lets take cherokee.chrysler.org.sg. It has 2 domains under it:
Original expiry was 21st Sept 2016. I renewed on 29th August 2016, but on
12th Sept, I still got this mail which shows the original expiry of 21st
*firstname.lastname@example.org email@example.com *firstname.lastname@example.orgMon,
Sep 12, 2016 at 5:13 AM
Your certificate (or certificates) for the names listed below will expire
in 10 days (on 21 Sep 16 21:15 +0000). Please make sure to renew your
certificate before then, or visitors to your website will encounter errors.
For any questions or support, please visit https://community.letsencrypt.
org/. Unfortunately, we can’t provide support by email.
If you are receiving this email in error, unsubscribe at
(HTTP link, we know. We’re working on it!)
The Let’s Encrypt Team
Its not only this domain by the way, I have a few, the expiry notice for
all of them have the same issues.