AIO

I’m a 33F and my gf is 35F. She dated/talked to another girl a while back before we became official. Well they talk on the phone from time to time, have gone to events while I still lived out of town and the girl ended up getting to drunk and had to stay at my gf’s house on the couch til morning…..I’m not the person to trip about things but I feel like that’s problem. When I start being too cool to refrain from being seen as “insecure” or “trippin.” We’ll fast forward to today it’s the girls daughters bday and my gf just got back from the gym said she had to shower and do something. I asked her what and she said she has to drop off to the girls daughter cause it’s her bday and she’s not staying long……honestly I’m not cool with it. Because if it were me gifting something to someone’s child after being with the parent, even though it’s “not like that” it wouldn’t fly with me ? So why should I let it fly with her ? I honestly trust her and I don’t think anything is going on…..I just think it’s doing too much and if it were me she wouldn’t believe “it’s not like that” and we’re “just friends” so am I overreacting ? Or is this really not okay ?