Word “regression?”

*Especially asking those who have another on the way*

My 23 month old son has been SO good at reactive words and phrases, “thank you” and “yes, please” being the main ones.

A few days back he started saying “you’re welcome” instead of thank you, and he’s hesitant to say please. I’m back to asking him what he should say and pressing him for the answers. It’s incredibly frustrating because I know he’s been doing well with words and understanding up until now.

My baby is due in February, so maybe he’s upped his attention-seeking? He doesn’t quite understand that he has another sibling coming, but he’s aware of my belly (pointing and saying “baby!”). I may be overthinking this, but I’m concerned.