Remus whipped his head to the other man in the shop, eyes round and face betraying the look of surprise even while he continued to catch his breath. He wasn't quite up to his standards of poise, the moon must probably be drawing closer...
One part of him scolded him for falling into a possible trap, chanting, This is a ruse! This is a ruse! in his mind but he couldn't help but be taken by the man who had just called him. He'd nearly stepped closer and said, "Frank?!" and he was about to produce the F-sound until he remembered in the nick of time that Frank was currently confined in St. Mungo's hospital back home, and there was no way -- wish as Remus might -- that he could just get on his feet and strut his way to New York 1964.
On the one hand, this man also lacked Frank's...fierceness. In fact, more than it, he had a bit of an...angelic quality? that wouldn't be quite characteristic of Frank, really.
But...
Wait, didn't he say "Gryffindor?"
The voice of the Sorting Hat shouting the House right at his ears reoccurred to Remus and he stifled a gasp as he said, "Yes!" flicking his young, graying locks off his face. What gave him away?
He looked down at his scarf. Oh.
But-- "You know Gryffindor," he went on more quietly to the older man just in case the old Muggle looking through his collection might overhear them. "You're a wizard?" A fellow wizard in New York 1964 and one he didn't know...fantastic!