Someone who lies about why they’re late will lie about bigger things when the stakes go up.

Small lies are not small in what they reveal. When someone invents a story to avoid a minor inconvenience, you have learned their default setting under pressure, and pressure only increases from there. Nobody tells the truth more readily as the cost of the truth rises.

Treat the little ones as information rather than as offenses worth arguing about. Watch whether it happens once or becomes a habit, and adjust what you rely on that person for. You can stay friendly with someone and still stop lending them things that matter.