Belyi's theorem says that if $X$ is a curve defined over a number field $K$ then $X_{\overline{K}}$ admits a map to $\mathbb{P}^1_{\overline{K}}$ which at most 3 branch points. Must there also exist a map to $\mathbb{P}^1_K$ defined over $K$?
This may be a slightly lazy question, but I figure it's probably got a quick answer.