Last week, I handed something to Vivienne and she said, "Thank you!" I have never heard her say that before (or at least I had not recognized that she was saying it). Whenever I empty the dishwasher, Miles and Viv will come running from the next room (because they hear the dishes clanging) to "help" me unload it. They mainly just take out the silverware and hand it to me one piece at a time. Though this significantly slows down the emptying process, I sit and take each piece one by one and exclaim, "Thank you! Thank you!" She must have learned it from me.
I've also noticed that she will occasionally hand me something and say,"Thank you." I think she thinks that "thank you" means "we're handing each other things." One step at a time, I suppose.