I've had this great job for over a year and was promised a promotion I didn't get based on my age?

Should I be looking for new work? I do love my job, and I don't work in the same office or even state as the woman that made the decision but I feel so cheated. They said at 23 I was not ready for the responsiobilty of the new job, but they didn't tell me this until after they already hired the new chick!