I 24M am upset over my girlfriend 23F kissing other girls and after asking if im ok with it. How to best communicate my issue with it?

Im 24M and my gf is 23F So last night my gf went on the night out with her friends, it was a girls night out. At some point she texts me with "is it cheating if I kiss another girl" I reply with "no, go for it" . She's been straight her whole life but sometimes kissed her female friends. Soon after she texts me with "good cuz I kissed 3 women tonight" Now im all for girls wilding out in a night out or whatever, kissing one of her friends is one thing, but kissing so many other girls is just plain disrespect in my view. Disrespect towards me and our relationship. Now she believes I'm being overly dramatic and that those mean nothing, but I can't shake the feeling that this is symptomatic of her feelings about the relationship, and that it may lead to something else in the long run. I mean if I feel upset there must be something to it. Does this mean she is experimenting, kissing 3 women is not a one and done type of deal. How can I better communicate my issue with her doing something first and then asking me how I would feel about it?