Mike's delay was not mysterious, merely worrisome to him.  He had managed to tie his left shoestring to his right - then had stood up, tripped himself, fallen flat, and, in so doing, jerked the knots almost hopelessly tight.  He had spent the rest of the time analysing his predicament, concluding correctly why he had failed, and slowly, slowly, slowly getting the snarl untied and the strings correctly tied, one bow to each shoe, unlinked.  He had not been aware that his dressing had taken long; he had simply been troubled that he had failed to repeat correctly something which Jill had already taught him.  He confessed his failure abjectly to her even though he had repaired it by the time she came to fetch him.