This, my girl did it soon after we got her and I didn't know what to think lol. Like Lexxie says as long as there is no signs of RI there is no problem.
After 5 mins in my tank my new BP (Monty yawned) , now the noise that came out of my snake hating wife was adorable. Something like the noise you make if you were surrounded by 100 puppy Labradors - Awwwwwww
My little girl will yawn, usually within a few minutes of holding her in the early evening. Being nocturnal, I figured she was just waking up. I always miss the camera shot though. Lol She also does it after eating too, but I know that’s to re-set her jaw.