Starting at 5:27 PM PDT, there were delays delivering scheduled CloudWatch events. Recovery began at 7:36 PM PDT, and by 9:22 PM PDT the backlog of all previously scheduled CloudWatch events was successfully delivered. AWS Lambda functions that were configured to be triggered from scheduled CloudWatch events are now being invoked normally. During this entire duration all other kinds of CloudWatch events and other Lambda function invocations continued to operate normally. All issues are fully resolved and the services are operating normally.

from Amazon Web Services Service Status