Boto RequestExpired

When running long processes I keep getting: ... content_repl/replicate_content.py", line 667, in detach_and_delete volumes = ec2_conn.get_all_volumes(volume_ids=volumes_ids) File "/usr/lib/python2.7/site-packages/boto/ec2/connection.py", line 2158, in get_all_volumes [('item', Volume)], verb='POST') File "/usr/lib/python2.7/site-packages/boto/connection.py", line 1186, in get_list raise self.ResponseError(response.status, response.reason, body) boto.exception.EC2ResponseError: EC2ResponseError: 400 Bad Request <?xml version="1.0" encoding="UTF-8"?> <Response><Errors><Error><Code>RequestExpired</Code><Message>Request has expired.</Message></Error></Errors><RequestID>xxxxxxxx</RequestID></Response> Note that many operations are performed along the script without problems. At the beginning of the script I have: ec2_conn = boto.ec2.connect_to_region(AWS_REGION, aws_access_key_id=assumedRoleObject.credentials.access_key, aws_secret_access_key=assumedRoleObject.credentials.secret_key, security_token=assumedRoleObject.credentials.session_token,proxy=PROXY,proxy_por=PROXY_PORT) Reading Boto connect_xxx method and connection pools and Boto docs my understanding is that Boto should handle connections internally and get a new one when needed. Is that correct? Should I add a parameter for that? Implement some retry logic myself? Btw, I'm using v2.40. The app is single threaded.