“I thought there was only a mileage requirement and not a time requirement for timing belt replacement.”
I believe that every type of preventive maintenance (with the exception of tire rotations) has both an odometer mileage value and an elapsed time value. Because the OP may have skipped other types of vital maintenance, I would recommend that he re-read the Honda maintenance schedule, just to make sure that nothing else has been skipped, in addition to the timing belt.
When he re-reads that maintenance schedule, I believe he will see that, with the exception of tire rotations, all maintenance procedures have both an odometer mileage value and an elapsed time value.