This is a common practice for the TSA (Transportation Safety Administration). There is usually a piece of paper indicating that they searched the bag and explaining why (the organization was created after 9/11). If you have a non-TSA approved lock, they always cut them off. I suppose it is a bit of a violation, but we've lived with it for years now and not too many complaints. They normally tell you when you drop off the bag for screening, so there was definitely a miss on that one.
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