Some people don't have time to wind down from Camp Fuckalot. Optimus being one of them. Because in trying to return to a normal routine, he'd learned that Sentinel had lost his T-Cog, and thus, couldn't transform into his vehicle mode. Most people wouldn't care--after all, it was Sentinel.

But you know Optimus. He's a people pleasing kind of a guy.

When told it was Megatron who had removed it...all that was left to do was find him. And really, Occam's Razor on that one. The Decepticon house was the most likely location other than the medibay, so he'd stop by there first.

Hi. Just the leader of the Autobots walking into Club D-Con.