Remus could have guessed at a few different reactions Sidda might've had for him. She might've laughed, or scoffed at him for clearly making fun of her. She could've gotten mad that he wasn't taking this seriously, or she could've freaked out thinking it was a trick. Or any number of possible reactions, but this... this wouldn't have featured even in his top 50 guesses.
He gaped at her in shock for a moment before he could think to respond. "You're serious? It happened to you too?" Remus had never considered mentioning to anyone else, but there she was saying that someone else in his own world had experienced something eerily similar.
"Were there other people there? Like from different worlds, different times?"