What do you think about this? Am I being paranoid or is this weird?

My friend has 6 year old twins. She is split from her husband, but both are in new relationships. It’s supposed to be her husbands weekends with the kids, but he cannot take them. The girlfriend of 1.5years has asked if she can take the kids for the night, even though the kids dad won’t be there. Is this… weird? Or am I just paranoid?