I would call ASAP and inform him that payment was due yesterday and you need him to swing by and drop it off today or do an EMT if your bank allows that to avoid a 'late payment charge' so he is aware that if he does not get it today that that tomorrow there will be one!

IMO you should not have to go without payment because of things going on in their personal life ... if the wife normally handles paying this bill she should have either left post dated cheque for you OR ensured her husband had a sticky note on his head to remind him ... I bet $$ that their mortgage and other pertinent bills were paid in her absence ... their failure to plan does not mean YOU SUFFER!