That seems very quick. However a lot of factors can effect that. Water weight. Were you eating a really bad diet before and really cleaned it up. Went from very sedentary to very active?
If you have any symptoms such as peeing a lot, fruit breath and always thirsty, I would maybe see a doctor. (DKA can cause very fast weight loss like that)
Otherwise, that's great you lost weight that fast. Congrats to you and please share your success tips.