Gotcha. Sometimes it doesn't take much to get inflammation going. If there is any evidence of an abrasion or wound you can dab a bit of iodine onto it to disinfect, making sure to avoid the eyes. Is there anything in your enclosure that could scratch the animal? If the animal is eating and drinking normally I wouldn't be too worried about it as of yet. Monitor the size of the swelling daily. If it begins to increase over time I would seek a vet.