They do not absorb but she might have dropped early, or maybe she hasn't eaten much lately. Much of the color that we see in guppies is little more than a full belly. The same goes for a round shape. If there is no squaring off, there is no nearby drop coming. At your extremely warm temperature any developing fry will definitely come sooner but that is not the ideal situation. My guppy tank only runs about 22C and I get robustly healthy fry that almost all survive. I also keep my females well fed but not overfed. That can be a fine line to tread. That way I have high fry survival with almost no efforts at all.
Water from an existing tank is nice but do you have a cycled filter? If not, you will soon remove all of that water with water changes to maintain pristine water conditions. If that is a new tank, be sure to stay on top of the water testing and be ready for lots of big water changes.