Baby kicking a lot at night?

Addi • Baby #2 due Jan 22!
My 9 week old has recently started kicking around at night like he is uncomfortable. He grunts a lot while doing this and it keeps me up. I can't quite figure out what it is... gas? He sleeps at an incline to help the reflux and that has always worked well. Could he be outgrowing the lounger he's sleeping in? Anyone else have this?