Papa Roe

We were in heavy traffic the other day (freeway speed), and I had to really step on it to change lanes. The transmission shifted down and the engine sounded like it wanted to jump right out of the car. I did get the lane change, but now I notice while idling at a red light there is a tapping sound that does match the engine RMP's. I'm afraid that I may had damaged a valve stem or something. What do you all think?