I just tried it with the new driver RedshiftJDBC42-1.2.8.1005.jar. It would failed with following error intermittently. I tried doing the same with sql/workbench and it seem stable and able to connect time after time.
Amazon](600000) Error setting/closing connection: General SSLEngine problem
driver class: com.amazon.redshift.jdbc.Driver
URL parameters: ssl=true&sslmode=verify-full
