Baby startling self awake, arms flying?

I don't recall my first one doing this. My 12 week old has been startling herself awake during naps on her Mamaroo. Her arms fly up and we feel so bad because it must scare her like crazy. I'm sharing this picture of Geodude because it's basically what her arms do when she startles herself awake lol. Even if there's no noise going on, it still happens. Is this normal??