Grinding gums?

I've noticed in the last week a weird popping noise coming from my son's closed mouth sometimes. It almost sounded like teeth grinding, but he has no teeth yet. Then today he did it when we were at my mom's and she said she thinks he's grinding his gums together. Anyone notice anything similar? Could it be a way of relieving his gums if he's teething? It's creeping me out. 😂