It is possible, lasue, that he was having some physical issues at the time. Recall that we wondered why he seemed so full faced - different from when he did the pilot (it wasn't just that he had his own hair in the pilot and a wig in the series; his face was puffy).
He looked that way a number of years ago, after he screwed up his back and was taking steroids to reduce inflammation. Maybe he hurt himself while he was working on the two or three films that he did between the pilot and the series filming?