Maybe he had an emergency of some sort? I used to work at a placement service and we had people do that sort of thing all the time. Sometimes, there was a valid excuse and they truly were unable to call in. Most of the time, they had to show an attempt to obtain employment to avoid jail for nonpayment of child support or something of that nature.
We have attendance issues as the most common reason they don't stay. A recent one was told beforehand that he needed a doctor's note for any more absences. So he missed work and then came to work without a note. Said he couldn't afford a doctor. But you can afford to be unemployed?