He was recently a bit dehydrated when I got him but now he's doing better and eating a small mouse every 4 to 5 days so I'm hoping he'll gain the weight back that he lost. It's probably a good idea just to get a scale now anyway since I'm sure I'll want one eventually. I'm guessing based on what people have said that he's just a generally small baby and not underweight anymore. He doesn't look skinny at all anymore like he did when he wasn't eating.