hmm honey maybe she's reacting to your impending new baby? She may feel she's not getting your full attention and is trying to gain others.
Make a passing joke of it to her...ah daddy smacked you..oh thats no good is it...and leave it at that. Dont over react to it babe...dont get upset about it either...she'll feed of it.
And babe, we know (We'll I do anyway) that you guys dont go tot he extreme of what some people may think. your wonderful parents.