Fizban's use of metric

In Dragons of Spring Dawning there is the passage: “Go ahead!” Fizban snapped at Caramon irritably. “I’m concentrating. I have to set the span down in the right place. A few more centimeters to the left, I think—”

Does anyone know why Fizban suddenly uses metric? Is it just an error or is it supposed to hint at the otherwordly nature of Fizban?