Prom Question.. if anyone is willing to answer!?

I wouldn't sweat it. If she really was upset about it or had no interest then she wouldn't have said yes in the first place. If you've gone out with her before then she has somewhat interest in you. The reason she probably said that to your friend was because most girls like to be asked to prom in a "cute" and "original" way as opposed to just straight up being asked. She probably would have preferred for you to have asked her in a different way that wouldn't have been as awkward from what it sounds like. Maybe to make up for it you could get her like one of those prom bears from build-a-bear to make it official (one of my friends did that for this girl he asked and she loved it). But honestly, I wouldn't worry about it too much. Have fun at prom.