There had been a rebuttal on his vocalizer, but it dies. The hand on the shoulder stops him. Optimus' words hit harder than what is likely intended by the much larger Autobot.

"Optimus."

What does one even say to that? Bumblebee has had doubts about how important he could have possibly have been. Optimus admitting this openly? Who wouldn't it hit pretty hard? Bee sighs and nods.