Weird question

Samantha

My daughter breastfeeds. She also takes a bottle while I am at work. Anyways the last two days while breastfeeding she has been sticking a finger in her mouth while my nipple is also in her mouth. Not every single time. But at night and when she is super sleepy. Is this normal? I should add she is almost 5 months old and absolutely will not take a binky. Maybe she is trying to self soothe? I just don’t know why she does it when she is eating.