Daphne is quickly learning about "thank you" and manners.
However, she did learn another use for saying, "thank you" and being cute.
When she wants something that I am holding, she points to it and says, "thank you." She does it as a preemptive way to keep me from saying no, and she assumes that she will get it anyway, so why not get the matter over with.
This worked today when she wanted the marker I was marking my garden with. A nice polite, preemptive, "thank you" got her exactly what she wanted.