Husbands very strange sleeping habit??

[MrsPhillips95]

Me and my Husband just recently married about 3 months ago. He had no idea he did this until I told him! Not every night but very, very often I will get woken up to him laying on his back and his arms straight up in the air! He just goes up and down slowly scratching his forearms while they're just straight up in the air. It's really freaky! He will do this for hours it seems. Last night I had trouble sleeping so it seemed I was awake every 30 minutes-1 hour and every time he would be doing this! I'm not sure how his arms don't get tired. I tried recording it so I could show him but each time the light to the camera would come on he would slowly just lay his arms back down as any "normal" person would sleep!
The first few times we kind of laughed it off and just thought it was strange but after him doing it almost the whole entire night last night I'm getting a little worried? I'm not sure if I should have him see a dr. If it's neurological or just a weird sleep condition? He's a slight hypochondriac so I don't want to worry him if I don't have to. But I really don't want something to be swept under the rug If it's a sign of something worse?? My mind always goes straight to the worst possible outcome.... what should I do????