Yeah, the startle reflex goes at around 12 weeks and so they say to wrap them until then so they don't wake themselves up. My DDs always got their arms out too though. I wrapped DD1 until 6 months and DD2 is still wrapped. Mainly bc she doesn't self-settle so it's way easier to put her down when she's asleep if she's wrapped otherwise she flings her arms around when she feels me trying to lower her into the cot and wakes up.