That's really about as cool as he should get, it wouldn't hurt to increase those temperatures by a degree or so. Also, if your house is going to get that cold over the winter you'll need to insulate the tank as the heat goes right out the glass sides - I know because my house stayed at 60-68*F last year and some of my guys hadn't been moved into the herp room (which I keep warm) when the weather changed. An easy way to do it is to fold up a blanket so it's the height of the tank, wrap it around the tank, and bungie-cord it into place. It looks silly as heck but it works.