We'll be performing routine system maintenance on Thursday, May 13th from approximately 6:00pm to 6:30pm PDT. You won't be able to access AdWords or the API during this time frame, but your ads will continue to run as normal.
While, AdWords system maintenance typically occurs on the second Saturday of each month, this update was delayed due to the Mother's Day holiday in the U.S. last weekend. We apologize for the late notice.
- Eric Koleda, AdWords API Team