10 months Mirena Period

I've had my Mirena IUD for almost exactly 10 months to the day and out of no where I got a period today. I haven't had a period at all since I got it put in but all of a sudden today I had horrible camps and went to the bathroom and there's my period. Has this happened to anyone else?? I'm very confused as to how this happened and why now since I haven't had a period since I got it. Let me know your stories!