Milk drunk episodes


My daughter is 3 weeks old and after feedings, not all, gets milk drunk. I’ve seen things posted on this, it’s adorable, she smiles, my heart melts. But she has these little episodes with it, her eyes Klein to the side, she breathes a littles heavy, sighs, smiles. Is this normal?? My gut tells me no cause for concern since it doesn’t happen any other time, just after feeding. Has anyone had their little one do something like this? Just want to make sure I’m not missing something here.