Discovered a time drift issue between the vagrant/virtualbox vm and the host:
root@82879b06345b:/opt/tubular/s3debbie# telnet s3.amazonaws.com 80 Trying 54.231.16.136... Connected to s3-1.amazonaws.com. Escape character is '^]'. GET / HTTP/1.1
HTTP/1.1 400 Bad Request Transfer-Encoding: chunked Date: Sun, 14 Feb 2016 04:51:59 GMT <=== !!! Connection: close Server: AmazonS3
0
Connection closed by foreign host. root@82879b06345b:/opt/tubular/s3debbie# date -u Sun Feb 14 04:36:30 UTC 2016 <=== !!!