Why do my shoes come untied only once per day, in the morning?

[SlyFrog]

@Bosda Di'Chi of Tricor

Do your shoes get wet in the AM? By, say, walking through grass?

This could tighten/loosen laces, perhaps?

No on that one. I suppose there could be some humidity difference from the central air to the great outdoors, to the extent you can call the suburbs and city that.