So my daughter started doing this

She’s now 3 years old, I started noticing maybe about 2 months ago every time she goes to sleep she starts sucking on her bottom lip? Is this normal? She’s never done that before ever. That’s why it’s surprising for me. She could be asleep already and still sucks her bottom lip.

-I never gave her a pacifier when she was a bay she never wanted it

- She stopped drinking bottle at 8MO

-She uses now a cup for her age.

-There’s really no issues with her

But other than that idk where this lip sucking started ?