Would you be asking this question if she had said "I'd rather go back to the room and read?" or "...and play with legos" or "and do yoga"??? Or is it because it was something technology related taht you are asking about her being obsessed with something? Because growing up I was that kid that wanted to sit and read. When we went on vacation, I had my book with me. I remember being at a zoo and just sitting on a bench and reading while my family was looking at the animals. To me, reading was more fun and relaxing. But nobody ever worried about 'is she addicted to books?' instead it was seen as a positive thing. Trust me, the minecraft thing is a very involved and intricate creative thing....you might be impressed if a child was building a replica dollhouse of the White House, well my 10 year old child has a built a full replica of Hogwarts, the Hogwarts grounds, Diagaon Alley, and Hogsmeade in Minecraft. One is just as creative and valid as the other, but people would worry 'oh that child plays too much minecraft' but I doubt I'd ever hear anyone say 'oh, he spends too much time building a dollhouse version of the Harry Potter Universe". Don't criticize just because it involves technology.