Thank you said by a two year old

When Jilliann says, "thank you" the words just melt my heart. She says it for the littlest things, things like putting on her shoes while she balances on my shoulder. Or after I wipe her bum, or get her cleaned up and set down from her booster seat at meal time. She is so sincere and the words come out so tender and as if she's really contemplated the situation. If I don't respond right away, she'll repeat her "thank you" until I've replied. Maybe it's because I know the social expectations that expect a "thank you" aren't yet embedded in her thinking....or are they? Maybe it's because I love doing these little things for her and it's my pleasure and I don't really need a thank you. Maybe it's because it makes her seem a little vulnerable, as she realizes she couldn't do these things herself and so I realize I'm her main caretaker and I like that. I like her.