I'm not sure if he RG3 broke it but he's pretty close to break most rushing yards for a rookie QB.
Rookie records are no big deal. If he breaks most rushing yards for a QB in history, then he's accomplished something.
Just a fun fact. It's a little over 700, I'm pretty sure Vick has the record with barely over 1,000. Though I'd say some rookie record are pretty big and will be hard to break like Moss's receiving TD's and Newton's Rushing TD's.