First off Ian is such a cutie! My daughter Molly is almost 10 and has Classical PKU. Her levels are typically between 3 and 4. Once they bump up to 4.5 to 6 (still within the acceptable range) her mood changes. She is more emotional and has a harder time keeping it together. Another friend whose child has CPKU says the same about her son. While some people experience no changes with mildly fluctuating levels, some people are just more sensitive to subtle changes.