General Feeding Checkup, still hungry?

So, I got a new ball and today was the first time I fed it. Since the store I went too only had frozen and the previous owner said he fed it both I went ahead and got a small frozen rat. I thawed/warmed and just dropped it in. He took it no hesitation (I skipped a feeding since I got him 2 days before the regular scheduled feeding and I didn't want him to not eat). I got a small rat (roughly 4 to 5 weeks old I am guessing), he ate it fairly quickly then started sniffing at me looking around pretty openly. Is that a sign he's hungry or needs a bigger rat?

So, medium rat next time? He is an adult around 4ft long if that helps. Are snakes like other reptiles where they will eat till they bust or can you trust them to know they've had enough? The previous owner was feeding once a week so I plan on sticking with that schedule for now.

the general rule of thumb is to give it a feeder approximately the same size as the snakes girth at its largest point. a ball that size should easily be ready for medium to large rats. for example my bumble bee ball python is around 800 grams and a little over 3ft long, i feed him small to medium rats (i kind of just eyeball the size of the rat compared to the balls girth)