What do you want him to do, produce a time card? A signed note from his boss?
Well, I've cracked a joke about him needing to provide a signed note from his parents next time it happens (I'm a teacher). Seems like this time the joke didn't fall flat, so hopefully we've cleared our disagreement out?
Honestly, a lot of speculation on my part as I cannot know about his actual work schedule, so perhaps the guy really just had to work overtime all week. Who knows.
I think this is a good way to discuss DnD and commitment. I'm appreciating hearing the different replies and opinions here.