i just got back with my AP. In the costums, I gave my 3 AP and passport to a officer,he asked me to go to an office to finish my paper work. In the costums' office I waited about 15mins to get one of my AP stamped with a parole period(one year). They didn't ask me any question. Actually it only took a few mins for my case. The officer checked my passport and AP. I think they have my information in the computer.
Just in case, I think you should bring some documents with you to approve your status, like copy of I140 approve notice. letter from your company human resources.
Good luck