The timing seems just too close to be even considered a coincidence. I think this is definitely the work of your Djinns. You may want to see, over time, if you can find out what happened to the horse you did "want" and did not get. I would not be at all surprised if there was something with that horse (that you did not get) that would have caused you distress (i.e. it had a "hidden" ailment or a "bad" temperament, etc). From what I have read on this forum spirits have a way of guiding you away from things that are not right for you and guiding you toward things that are "best" for you. It seems clear that you got a horse that is "best" for you, the only thing you don't know right now (and you may not even care about) is why the other one that you thought was for you really was not "best" for you.
I hope you and your djinns enjoy your new horse. Please give the horse a hug for me.
Quod est inferius est sicut quod est superius et quod est superius est sicut quod est inferius, ad perpetranda miracula rei unius - Hermes Trismegistus