Copper IUD: Use a condom for 6 weeks in addition to the IUD?

Hey guys, I had the copper IUD inserted today, and at the end, she told me I should use a condom for six weeks until my follow-up appointment to prevent the IUD from slipping out of place. To be honest, it sounds pointless to me. I mean, I don't understand the difference between how a condom is supposed to prevent the IUD from slipping out of place. Does anyone have an answer? I could have asked her myself, but I wasn't really able to after the insertion. 🙈