There was one more glitch from the certificate provider, but things have been smooth since, so marking this as resolved.
Posted Apr 20, 2018 - 16:21 AEST
Monitoring
Marking this issue as resolved given the certificate is now correct again. Will continue to monitor for any affected services.
Posted Apr 20, 2018 - 14:42 AEST
Identified
As part of some DNS changes, SSL requests for flying-sphinx.com were briefly returning an invalid certificate (lasting about 10 minutes). This has been resolved, but if you're seeing the problem persist, please do get in touch.