"type": "urn:acme:error:rateLimited", 3:38 PM "detail": "Error creating new cert :: too many certificates already issued for exact set of domains: mx-out02.wmflabs.org: see https://letsencrypt.org/docs/rate-limits/",
This may be from recent puppet refactors. This might be a good time to adopt acme-chief here if it's not used already; I believe we have a working acme-chief install in that project already.