I also have the latest copy of the USPS shipping module ("The USPS Shipping module v4.0 supporting USPS API v3"), I had my USPS account moved to production, I turned on error reporting on the front end, and turned off failover, and I get nothing!
All I get on checkout is "Please select a Shipping Method!" and no error message and no options to select.
I am using VM1.1.1 and J1.5.3