I agree, it's either due to infertile eggs developing, or it's due to her just waking up from her brumation, although if she's been out of brumation for a month, then it's most likely not that. If you've checked all 3 of her temperature zones with either a temperature gun or a Digital Probe Thermometer and all 3 are within the correct ranges, and her UVB tube is mounted correctly (if it's the T8 tube version of the Reptisun 10.0 then it must be mounted underneath any mesh lid to the tank and within 6" of her basking spot, the T8 tubes are too weak to be blocked by the mesh lid and still emit adequate
UVB light to your dragon on the other side).
As long as you've checked the temps and have the UVB tube mounted correctly, then it does sound like eggs. As AHBD instructed, the easiest way to find out is to make her a laybox by using a large, plastic tube and piling damp (but not wet or soaked) playsand on one side of the laybox. Make a hill on one side of the tub, and then start a little tunnel about half way up the hill for her, then put her beside the hold. Keep her in for an hour or two, and if she doesn't start digging then you can put her back in her tank, and when she starts glass-surfing again then put her back in the laybox. It sometimes takes a while for them to be ready to lay the eggs.
I mentioned checking all 3 temperature zones with a Probe or Gun because you mentioned the "stress lines" on her belly, and these are not "stress lines" at all, that's a myth that somehow got spread around the internet and caught on unfortunately. The markings on their bellies are just that, markings, just like the markings on the rest of their bodies. And they darken the markings on their bellies along with the rest of their bodies when they are inside their tanks and under their lights, as they are trying to attract/absorb more light/heat. This is also why they always lighten/brighten their colors up when you take them out of their tanks, because they are no longer under the lights anymore, so they don't need to darken themselves to attract the lights. So sometimes when they darken themselves inside their tanks it's perfectly normal and they are just trying to attract as much light/heat as they can, but sometimes they stay that way constantly inside their tanks because their temps are too low, or because THEY ARE NOT GETTING ENOUGH UVB/UVA LIGHT, SUCH AS IF THEIR UVB TUBE IS THE WEAKER T8 STRENGTH, AND IS BEING OBSTRUCTED BY A MESH LID TO THE TANK, WHICH BLOCKS ABOUT 40% OF THE ALREADY WEAK T8 UVB TUBE. This is why all T8 UVB tubes, even the high-quality Reptisun 10.0 T8 and the Arcadia 10% T8 tubes, must all be mounted to the underside of the mesh lid.