[souffle]

Hi and welcome
Hamsters do sometimes carry food round and it happens that when you look at them they always seem to have a full pouch however if you have suddenly noticed this and it is one sided it could be either an impacted pouch or an abscess in the pouch. Sometimes something will jab the lining like a sharp seed and cause an infection to form. Usually you will find the breath smells bad if this is the case and the hammy may keep pushing at the cheek with her paw. If it stays and you can feel a hard lump or a squishy mass when you touch it then you should see the vets. They can empry an impacted pouch or abscess and flush it out then treat with antibiotics. I would try and find an exotic specialist vet though.
Sometimes if they have had a little fright from maybe fireworks or you have done a clean out recently they will feel a little insecure and keep wandering around with their food in the pouch. Make sure she has plenty to store and don't overclean the cage with a young hamster. They need to have their scent around to feel safe. Just do spot cleans of the wet corner.