Does he strike you as the sort of person who would actually take off for a headache?
I don't know, I can't judge that kind of thing about people. Never had had that kind of intuition.
I've known him for a while and I've generally found that I can take things he says at face value
If you have known him long enough to take most of what he says at face value, let it rest.
Maybe he has a really bad headache, something so crippling he can't work through it.
Or maybe he is lying to you because he doesn't want you to know the real reason he is taking off.
Maybe his cat died and he didn't want to seem like a pussy.
Maybe his Son OD'd and he doesn't want to seem like a bad Father to his coworkers.
Maybe he was actually attempted suicide and got 302'd.
It really could be anything. It could even be a headache.
The point is, most people I know just seem to take time because "Oh I hurt today." What the fuck?