You might think about the plastic top being or getting heated by the Lamp which could send toxic fumes into the air and tank, you stated she was fine until you did that it's worth investigating... Plastics that are not designed for heat do strange things. Just a thought in trying to find the problem....
Also check at TheBigCheese.com for ordering your Frozen mice you pay 29.00 for delivery they always arrive nice and frozen and you can make volcano plumes with the dry ice lol it's cheap entertainment don't let the kids do it without adult supervision.