My 10 week old will only nap for 30 mins. During the 30 mins nap, its usually quiet, but after the 30 min mark, she will start crying on and off until I get her up. I've tried going in and rocking her back to sleep, and she'll get sleepy again, but will still cry on and off. When it is quiet for a few mins I go in and check on her and it looks like she is sleeping. Should I leave her to continue fussing/crying, or should I be getting her up?

Usually, after the 30 min nap, she'll cry out for about 5 -10 mins. Then, it'll get quiet for a few mins and the on and off crying/whimpering will begin. What is this?