I wouldn't trip about the first missed payment. When you finally receive the payment, just ask: "Is this lateness something I should expect in the future? I was

I wouldn't trip about the first missed payment. When you finally receive the payment, just ask: "Is this lateness something I should expect in the future? I was pretty surprised by it. I didn't realize you would be missing any payment deadlines." Most people will feel embarrassed enough to auto-correct their behavior after being called on it. If it becomes a habitual problem, then you might need more aggressive actions.