Shock at Dusseldorf Airport

Last weekend I was taking a flight from Dusseldorf to Munich and I was standing in the queue to hand in my boarding card and board the plane. The man in front of me had an argument with the airline official and then, when it was my turn, the airline official took my ticket and said, under his breath, 'Sod off'. I was rather surprised and a bit offended. That was until half an hour later when I realised he'd actually said 'Dusseldorf' really quickly.