My ex has recently remarried, and she is now expecting a baby. She's been acting a little weird since she found out she was pregnant - not as communicative. Yesterday, when I picked my son up, I heard her refer to me by my first name, as in "Bill" is here to pick you up. Not Dad, Bill. This was surprising to me, and I think we should talk about it, but I'm not sure how to bring it up. What's good ex-etiquette?