I don't think this constitutes regifting - I have at times bought something for myself, and then someone else came along who really liked it and I gave it to them as a gift.
Well, that depends.....
If you bought yourself something, and someone saw it and really liked it, and you just handed it over to them, no, that's not regifting.
If you saw that someone really liked it, and you waited until a "special occasion" and wrapped it like a new gift, then it would fall under "regifting", although since you didn't receive it as a gift in the first place, I'm not sure of that.