Good evening, mommy ? Yesterday in the evening my son started arching …

Good evening, mommy ? Yesterday in the evening my son started arching his back, I immediately panicked, thought it was a spasm, but noticed that before he arched his back, he puts his feet in an comfortable position and as if he's lifting his bottom up. I think he's asking for help with the hands. I read that they can do this before getting the ability to roll over from tummy to back. I don't remember how it was with the older one.