I'm sorry! I misread your question. The temperature has to be at least 45-50 degree I think and can't go lower than 40 I believe. If it's any warmer than 50 degree, then you are essentially starving your turtle.

It could just be that the temperatuer may be too cold inside the house. I'd double check those temp with at least two thermometers so I can get an accurate reading... I like to use the digital ones.