FYI from Google:
Status: Service disruption
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 March 30, 2015 10:15:00 AM PDT 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.