As of July 12th 2016 at 15:30 UTC this issue has been resolved.
Posted Jul 14, 2016 - 10:23 UTC
Investigating
On July 12th 2016, beginning around 13:30 UTC, Dyn engineers began performing emergency maintenance on our Managed DNS API. Users interacting with the API may experience delayed transactions and elevated zone propagation times. No impact to Dyn Managed DNS Nameservers or other peripheral infrastructure is expected. Updates will continue to be posted as information becomes available.
We do not recommend that customers make any configuration changes in response to this maintenance. Customers with any questions are encouraged to reach out to our Technical Support Team.