That would be concerning..
I'd see if same thing happens again at next visit..
But be careful of any new things he brings up as it might be problematic for you..

It might be a one day fogginess, but if happens more often, maybe he is working when he shouldn't be..and no one in the office or family, will suggest there is a problem and he should not be working at this time..
He might be trying to keep working to get the income... but peoples lives are at stake in that profession..