I kiped this from Percy, silly. He'll never miss it.

Oh come on! After living with Fred & George, you don't think he's got detection spells up the wazoo in case anybody unauthorized so much as touches it!?

I mean, it's probably easy to find, since he would have a special place to put it when not being worn, but that would be nighttable or... Oh gee, now that he's left Hogwarts, do you think it might be framed and on his desk? [That's assuming Hogwarts lets the students keep their badges after leaving, and doesn't just reclaim and reuse them for the next incoming class.]