Since installing iOS9 on my 5s (and even after getting a 6s) I've noticed at various points, my recent contacts shows calls from up to a year ago. I keep the recent list clear, and it never did it until iOS9. I thought it was just a strange thing with the 5s, but since upgrading to the 6s and having it happen on it too, it must be an odd bug with iOS9. It's nothing more than a nuisance and I just clear them, but was wondering if anyone else has experienced this as well?