get rid of the hay its not good for chicks or chickens get pine shavings all it takes is a little mold on the hay and bang sick chickens and dead chicks
I live in Oregon and have always used a mixture of hay and Pine shavings... It gets cleaned out twice a week and new put down and I have never had one sick chick...
Since she is using a heating pad I doubt she would allow the hay that's both beneath it and over it to get wet