Someone please help me and is something wrong with Bailey?? About an hour ago Bailey was sitting very close by my foot and something told me to look down at him and his bottom jaw was trembling bad

it only last for like a minute or so and it was def. not cold in our home it was actually kinda warm because I left the heater on today by accident......So I asked hubby to put on the ceiling fan and just a min ago he started doing it again and I know he is not cold though and I am starting to get worried..I love this lil guy so much!!! Am I over acting?? Does this happen to your baby? He looks fine though and it only last for a minute or so. Advice is appreciated...Thanks