I think she is over stimulated.

When my son was around one month old. He become jumpy with any little sound. He ate a lot. But still get so jumpy with any sound. If he is sleeping on the bed, I walk into the room, 3 steps away, he would wave his hand like he get scared. Short wave, like up and down. Probably she is hungry but at the same time too tired. So she fall asleep 5 minutes during feeding. Wake up in 10 minutes and eat again, does she go back to sleep again? I made sure he finish his bottle before he get into deep sleep. Sometimes he just won't take in any more even after I keep touching his cheek. So I just let it go. He sleep better in people's arm. Still get jumpy with sound, but won't cry or wake up. Maybe feel more secured. Older people say 惊吓，even tried to put my hu*****and's shoes on top of him while he is sleeping, didn't work though.