I came back here on end of May this year. They did ask me the paper fom Ministry of Labor. I thought they were just giving me hard time. The officer told to talk to his manager after reviewing my PP and I-797 and the manager told me that i supposed to bring the document from Labor. I said i did not know anything about it and told him this is my 4th trip going to US with H1. He then gave me permission to pass through. It seems now that H1-b visa holder require to obtain documentation from Labor.