Roman had been caught off guard when he ran into Penny while picking up rations for him and Percy. The motel they were staying at wasn't too close to her house so they shouldn't have bumped into each other.
He wasn't supposed to see her in his usual appearance. It might throw things off too much. If she referenced the little meetup they had today to his younger self, they were going to be in real trouble.
He hadn't been able to resist when she wanted to spend a little time with Penny though. He had missed her so much while they had been stuck in the past.
Two years ago, he hadn't been able to see her at all. The only other time he saw her here was when he had to pretend to harass her and that had been a fairly terrible experience. He hadn't talked to her normally like this since before she died in his original timeline.