I have read that pacifier could help the baby self soothe himself/herself back to sleep. Hence, I think it is a good thing and you need not be too concerned about it. My friend's baby would cry when he/she wakes up in the middle of the night and realised that her pacifier has fell out. Once, she found it and popped it right back and went back to sleep all by herself. Other times, she would cry till it is back in her mouth. But my friend found that it is much easier (with the pacifier) to get her back to sleep as she need not pick her baby up to soothe or comfort her.
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