Another perspective is that a lot of companies would beg for this growth rate. Stock prices reflect future growth and the future looks good. Microsoft? The only way they win is if they buy VMW (won't happen). Their own product is not impressing anyone. Overreation to earnings? No... rather, a reaction to a turn-around situation. Market saturation ? Don't think so but that's just my opinion.
Enjoy your short position. As always, I hope you will make a profit as well.