I remember discussing this in adult Sunday school once and one of the class members said (paraphrasing): “I wonder if God whispered ‘Son, your message is not just for Jews but for the gentiles too.’”
I thought it was an interesting take, for this is the first time, that Jesus went to those beyound the Jews. Of course, I can’t remember when curing the Centurion’s son happened in relation to this, but the Centurion was one of the “judaized Romans” or whatever is the correct term.
The legend that I have heard is that the chosen people called the Gentiles “dogs.” Don’t know if it is correct or not.