It could be as simple as fatigue in the leg. He's been rehabbing it for three years after all. Supposing it was muscle fatigue, they would want him to sit because favoring a weak leg would increase the chance for injury.
Point being, it could be an innumerable amount of minor things. I wouldn't worry to much about it at this point. If he's sitting out the preseason games, you might want to worry a little bit more.
agreed with everything except the preseason games thing.
i see preseason as pretty meaningless except as a tryout for fringe players.
players that i the team is going to be relying on i really don't like them being exposed like they are in those situations where they can be on the wrong end of a guy trying to prove themselves and get knocked out for any amount of time or one of those players we rely on who don't know how to scale it back and end up getting hurt.
it's a game that has no bearing on the season. i have no problem with starting players seeing minimal time or no time at all in those games.