Are the fruits and veggies balanced to a 2:1 ratio? If they are not, then there is your answer. It HAS to be balanced. If it is not then the diet and the HPW are pretty much worthless.
Now, have you noticed this recently or has it been like this since you got him. If it's been this way since you got him then you know it started with the previous family. If it's new, though, it's a different story.