If someone is interested, I have found the problem and the solution.
Login in through ssh, I have found this error of the S3 upload script:
ERROR: ErrorRequestTimeTooSkewed 101
Message: The difference between the request time and the current time is too large.
Extra Details:
MaxAllowedSkewMilliseconds: 900000
RequestId: 943525BD92A127B8
HostId: 3G59SwUoC6FtCdryD+Z7nnE+FI6pY95gUF0boLBeKQXWhgo+Fs4JrN0j4FdKXSFW
RequestTime: Tue, 09 Apr 2013 18:59:49 GMT
ServerTime: 2013-04-09T20:00:05Z
In another words, it compare the local time with the server time, and if the local time is not correct, BANG!
The solution is simply adjust time and date, manually or setting a NTP server...