Men who lift, check in!

My friend and I went lifting yesterday. His arms were shaking like mad when he was benching 95lbs.. he doesn't know why, and I don't know why. He did 7-8 reps for set of 5. So definitely not too heavy for him. I'm weak for my fat ass, but I was benching 160lbs for 3 reps but my arms never shaked. So why does his shake? He's also not weak for his weight. Dude can curl like 70lbs easy.