Opinions needed. Is this considered cheating?

My partner (F26) and I (M28) are new to non monogamy, and opened our relationship a few months ago.

Last night, my partner met up with a potential connection for the first time. We mutually agreed beforehand that no physical interaction would take place between us and any potential connections on the first meetup/encounter.

When my partner arrived home, she stated to me that she and the potential connection kissed, and were physically affectionate to some extent, she stated the connection put his arm around her while watching a movie.

Is this considered a transgression or cheating?

I am not looking to bash or paint my partner in a bad light here. I am strictly looking for opinions as someone who is relatuvely new in practice to this lifestyle.