Yup. All Govies carry around a CAC, or Common Access Card, which among others things has an RF interface. The difference between this and US passports, for example, is that the passorts come with a handy booklet shield, that when closed, blocks RF. The CAC card has no such thing, unless suplemented with aftermarket holders, etc. Though, I don't believe much information can be gained as the CAC is a smart card - though I would imagine that you would at least have the knowledge of what it was you detected, but probably nothing further.