In the first posuk (Numbers 22:2) it says:
וירא בלק בן ציפור (And Balak the son of Tzippor Saw)
no mention of his Royal status, later on in the parsha (22:4) it says:
"ובלק בן ציפור מלך למואב (Balak the son of Tzippor was a King of Maov)
What happened that only later the torah tells us that he was king?