Blogger Websites Showing Some "Service Unavailable Error 503" Messages

Blogger was showing some  "Service Unavailable Error 503" on certain blog pages. Alerts only lasted a few moments.

No status alerts for Blogger.

Gmail status showed the following alert for March 30, 2015 at 11:15 AM ...

We're aware of a problem with Gmail affecting a significant subset of users. The affected users are able to access Gmail, but are seeing error messages and/or other unexpected behavior. We will provide an update by 3/30/15, 12:15 PM detailing when we expect to resolve the problem. Please note that this resolution time is an estimate and may change.
This is only affecting IMAP connections to Gmail.