I have a pair of Keen walking shoes, and they're wonderful. I've had them for about three years and wear them every day.
Now, however, I've noticed that my shoelaces come undone annoyingly often and quickly. I don't think it's how I tie them - I've always double-bow'd laces which are too long for a single, and I've not had this problem before.
I do know that feet get smaller and the like. But would this also have an effect on something like your shoelaces?