It's worth noting that Stephen never ran from the scene of a crime. Bumping into someone while under a Disillusionment Charm would have been hellishly uncomfortable, not to mention dangerous from the legal perspective of the laws he was living outside of. There was nothing like the horrible nightmare of bumping into some random Muggle and then potentially saying something and then potentially being apprehended...well, it wasn't the nicest thing to think about.
So he was very careful to be aware as he walked out of the bakery and onto the street. But what he wasn't expecting was for someone to say something to him. Shit. Wait. Maybe they'd just said it near him and he was overreacting. Stephen was quick to get out of the way of the door, and then turned around and looked at the man who he thought had spoken to him.
He was still looking at Stephen. Stephen stared back in return.
Okay, so looking at the man, Stephen was pretty sure he was a bit too inconspicuously dressed to be a Death Eater. Indeed, he looked more like a Muggle than a wizard. Maybe he was a Squib. Maybe he was another Muggle, failing to make a life in the world he'd been cast out into. Stephen had yet to gauge the importance of knowing precisely what the man was. In any case, he was presently standing outside a bakery talking to the air.
After looking at the man like a deer in the headlights for a bit, Stephen shook his head, then pointed to himself, some Muggles who were walking down the street, his eyes, and then made a slicing gesture with his hand, hoping the man would get the message. He then continued to walk.