Cat is chewing on nothing/licking his lips

Hello, my cat Samwise has recently in the last couple of weeks started this weird chewing/licking movement. He appears to be chewing on nothing or on air. He’s never really done this before.

It will most often be when he is laying down with me with his eyes closed and relaxing.

The biggest change route wise with him recently has been going on a diet, at the advice of his vet. Maybe this is just him signaling that he is hungry?

He is a 5 year old male, neutered. About 16 pounds. Typical domestic short hair.

I wanted to include video of the action and of his teeth. This sub doesn’t let me do so.

No other symptoms are present. He eats fine, sleeps fine and isn’t vomitting.

I’m worried he is stressed because of this and that this could flare up his feline herpes OR even worse cause a urinary blockage. He’s already gone through that once.

I have him scheduled for a vet visit next week.