Steve looked down at his uniform. "It's not as spangly as the last one was," he said, grumbling just a little. He liked his uniform. It was the mark of a soldier - soldiers wore uniforms. Otherwise they were just armed thugs.
"I remember where my room is," he said. "Unless you changed it." But he was still grinning as he headed down the corridors to find the room he'd been given so many years ago.
It was still small. As in, fit for his pre-serum body. After a few minutes of nostalgically browsing through the room, Steve made his way to the wardrobe, found some civvies, and went back to the control room.
Yeah, Stark was probably going to be pissed that he'd left. If the billionaire didn't outright assume that the alien had kidnapped Captain America.