Peeta had never really thought about the prospect of Katniss and Anna meeting. That was probably because, as far as Katniss went, he wasn't certain if they were friends or just ... Dreammates or something. He wasn't sure how to approach her, in any case.
So he was surprised to walk into the Pie Hole and literally walk into her.
"Katniss!" Peeta exclaimed, blinking. He was about to ask if she was fine, when he glanced over her shoulder and saw - "Anna!"