In Transformers: Dark of the Moon (2011), Optimus offers Sentinel the Matrix of Leadership and to lead the Autobots again, but he refuses as he secretly plans to betray him. The Matrix only merges with those considered noble of heart. Sentinel knows he is no longer worthy and lies to keep his cover.

When Sam first held the Matrix in *Transformers: Revenge of the Fallen* (2009), it crumbled to dust. Then he put all the dust into that sock, and when he “sacrificed” his life to save Optimus and had that “vision” with the Primes, they say he was now worthy and the Matrix comes back one piece. Sentinel passed it back to Optimus as a method of covering his tracks, especially since he had no use for it.