I've had my bedding nicked when seated in the front row of CW and the entire plane entered between CW and F. It was the late flight from LHR-DXB and I didn't notice until I woke up, cold, about 3 hours into the flight. Amazingly, when I asked if there was any spare bedding, I was basically shooed away by the crew member in the galley who said it was my fault, somehow. (However, his colleague overheard this and immediately got me a spare blanket from F). So yes, it does happen - but at least your crew did what they could to help.