Is coparenting dogs with your ex normal or am I just being insecure? (28f, 32f)

I (28f) have been dating my gf (32f) for about 8 months now. She previously dated someone for 10 years before me and they had 3 dogs together. When they split, her ex took two of the dogs and my gf kept one. They regularly go over to each other’s to swap dogs, send pictures and videos of the dog and seem to still bond over them and use the dogs as a way to keep in touch. It feels a bit excessive and unnecessary to me. I’ve had pets with my exes and when we split, the pets would just go with one or the other.

Is coparenting pets with your ex a normal thing or am I maybe just being insecure?

Edit: The other aspect that makes me uncomfortable about this is that they only message each other on snapchat. She says it’s because she got a new number and didn’t want to give it to him but it feels a bit sus to me.