How long did you leave her out for? What was the temperature at and were there shady places she could retreat to in order to regulate her temps? Gotta watch out for overheating. Little ones can easily overheat since they're so small. Also, I think I've read that once they overheat, they're more likely to be susceptible to it in the future. Hope she's all better now.
overheated for sure. Don't take them out when its overly hot out. Provide a soaking dish so she can climb in it outside if she feels warm. Provide a shaded area to go into as well. Keep it short and sweet if its super hot out. It'd be perfectly fine if the tort only gets 2 30 minute sessions a week outside. She will get ample UVB.