Just another odd occurance of setting off the scanners. At MCO, I was holding my passport that was in an RFD cover. The RFD cover set off the scanner. TSA couldn't figure out what was setting the scanner off. TSA kept asking me if I had an artificial hip....etc. FINALLY another TSA guy from another lane and came over to help as he knew what the problem was. He asked for my passport and sent me back through the scanner....Voila, problem solved. He said some sleeves do this and some don't. Normally I put everything in the carry-on but was told to hang on to the passport for a secondary screening. Next time, sleeve and passport stays in the carry-on, I will pull it out for the next screening.