I'm a newby @ this & really need some help. We gave my son 2 uro's for Christmas & they have been great, they have recently found the PVC pipe tunnel we put in when my husband built the tank it's 2 ft deep w/sand for them to tunnel. But they haven't come out for 3 day's. We check on them & keep the lights & heaters on up top to keep heat in but we are worried to death. They aren't coming up to eat or visit anymore. Is this normal???? Any input is appreciated. A very worried mama.