A recent release changed the way timestamps are represented in webhook post bodies. They changed from this format:
2012-05-24 17:28:24 -0400
To this format:
Thu May 24 17:28:24 -0400 2012
We are preparing a release to restore the original functionality.
We will also soon be announcing our API for Webhooks, which you can preview on our documentation site: http://docs.chargify.com/api-webhooks.
We also have a new beta feature: a "Webhooks Panel" which allows you to review all webhooks and selectively replay them. This feature may not be available on all plans going forward, but if you would like preview access please open a support ticket requesting access.