I got these emails too and everything worked well for me.
The email also said:
For details about when we send these emails, please visit
https://letsencrypt.org/docs/expiration-emails/. In particular, note
that this reminder email is still sent if you've obtained a slightly
different certificate by adding or removing names. If you've replaced
this certificate with a newer one that covers more or fewer names
than the list above, you may be able to ignore this message.
Maybe added or removed names?
It looks like picolisp.com was renewed on 2017-05-21, see