Give his casque a gentle squeeze between your fingers - preferably when he's asleep. If it gives, and bends a bit, he' sgot slight mbd probably. They can easily get a minor case when they're growing, and you'll never see major signs of it, as they recover when they slow down their growth rate. Regardless, you want to get him some more calcium and D3, as well as UVB lighting, if he's got MBD. Sometimes, when they're little, they get it for just a short time,and the casque is permanantly bent. Some of them just seem to develop a misshappen casque, but usually not like the pic above - that looks as if it was caused by MBd.