Thumb sucking baby

I caught my daughter thumb sucking one time and from then on she has been doing it for fun or whatever. Do I have to worry? I don’t really know. We used to have a neighbor back home in the Philippines where thumb sucking became her bad habit. Imagine she was already in grades school and still she was doing it. Her parent and grandparents tried to do all they can to stop her from doing it but she just can’t refrain herself from doing it. Her thumb looks ugly and deformed from sucking it all the time and I don’t want that to happen to my daughter. I was so concerned, so I searched online about it to get some answer to my few questions. I found out that thumb sucking is normal for a newborn because it helps them calm themselves, which I agree 100% and besides its their inborn reflex. Well, before babies were born they've already started thumb sucking inside the uterus and they might have already acquired the taste of their thumb that’s why they were doing it. So I guess I shouldn’t let it bother me for now because it’s good for her… We’ll see what happens in the future.