I need a female's point of view?

My fiancee had girls night out about a month ago. I was going through her Facebook friends and came across two unknown guys. I asked her about them and she said all the girls met them that night , yet she's the only one that has them as friends. She says their only friends and that I'm overreacting. Last night we had dinner and she waved at a guy from far and I asked her who that was and she said it was one of the guys. It's weird to me how they would still even know each other that good after a month. I'm I being jealous and unsecured by getting mad? Is she doing right by meeting guy friends when she goes out? Thank you ladies for your answers.