Firstly, 24 hours after feeding is, in the opinions of most on here, too soon to handle. 48 hours is the general rule. They CAN regurgitate if held too soon after feeding, and her behavior MAY be related to being handled on a full stomach.

But I am still unclear as to the nature of her behavior. If it is just a quick open wide and close, then it is just a "yawn." Snakes' jaws are segmented and not attached to the rest of their skeleton, so they have to periodically stretch their mouth out to realign their jaw bones. No big deal at all (unless you see bubbles and mucus).

Regardless, if you got the snake from PetCo/ Petsmart, I would take it to an exotics vet ASAP. They are not known for selling healthy animals. I personally would never buy an animal from them (but that is just me) but if I did, I would take it to a vet straight away. A good exotics vet can tell you if it has parasites or any underlying health conditions. They can also properly sex it for you.