Ah, my memory was from late Saturday night after a couple of celebratory beers. Having watched that I agree with you. He is patting his pocket which means that he thinks it should be a booking (it's where they usually keep their yellow cards). Of course, he may just be checking that he hasn't dropped his wallet. Red cards are often kept in a back pocket so if he pats that it shows that he thinks it should be a red card. Or that he has an itchy bottom.