Rondo is definitely shooting more from outside than he normally does. While it would be nice to see him add a consistent 3-point shot to his repertoire, I wonder if he's penetrating less / finishing less at the rim due to rust or residual effects from the injury.
As for the percentages, just keep in mind what a small sample size we're talking about. Before last night, his 3PT% was around 29%, which is poor; one hot game shot it up to 38% (which is very good).