I feel like such a dick. I've been lifting (and benching) for 4-5 years, and this is the first time I ever did this.
I'm not sure if all benches are designed the same way, but the ones in my gym have these two little cylinder shaped pegs that stick out above you so that you can put the bar on it/take the bar off it when benching.
Somehow I managed to bang the bar into one of the pegs while pressing it upwards on like the second rep.
I must have somehow positioned myself too bar back on the bench or something. Who know. All I know is it totally screwed up that set, and then it was all I could think about in the sets after that.
Anyone else ever accidentally do this? It would help me feel like less of a moron.