should I be jealous, or was it just a joke?

Ja
My boyfriend and one of his friends who is a girl were joking around earlier today. I am also friends with her, so it's not like I'm afraid she's trying to take him away from me or anything. I was catching up on some studying while they were right next to me laughing and being goofy, and if occasionally jump in for a second and then go back to my studies. 
At one point my boyfriend said something that I didn't quite hear, but then she laughed really hard and said "You're so funny! God I love you!" And I immediately stopped what I was doing. My boyfriend had a very confused/ shocked look on his face while staring at her. She just kept laughing, then said she had to go to class. She didn't even acknowledge what she did, just said bye and left.
I looked over at my boyfriend who was already looking at me. I mocked her and said "God I love you!". He rolled his eyes, and mocked her too and said "OMG YOU'RE SO FUNNY!" In a valley girl like accent.
I know he isn't doing anything behind my back, but should I of gotten so mad? She's a friend, and I introduced them, but I don't feel comfortable with her saying that to him.

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