Tiger has done the same thing. He used to do "super jumps" after the feather toy and one day, he just landed wrong and limped off and on for a week.
We sort of ended the practice of enticing him to jump that high anymore. It took about 2 weeks for him to completely get over favoring the leg and start running up and down the hallways again.
We just don't think about cats spraining something - they are usually so flexible and agile!