I don't believe it's anything to worry about, but speaking to your vet next time you are there will put your mind at rest.

Good luck x0x

I remember hearing years ago in relation to cats, it was them practicing their bite. (Like when they are watching birds from the window.)

Willow does this sometimes when she's in the car, usually when we are heading out somewhere rather than returning home. I put it down to excitement, cos the car means mainly lovely walks for her, or visiting my parents house, or the vets who she's always loves to go see. (Though not as keen on the treatment room, lol.)