Startled when sleeping

Hello mummies, for the past few nights we noticed that our baby (3months old) got startled and cry when she is sleeping and the timing is always around 9plus 10plus in the evening. When I say startled and cry it feels as if like baby got a nightmare and woke up from a nightmare kind. But what I do know is babies don’t get dreams till they are above 1 or 2 years old. In the day time or when baby is awake, she is happy though. I wonder what is the cause of the “startled and crying” Anyone can advise me on this or is it a concern for me to see the PD.