Some people asked why it took her 8 months to find out [3]: she was studying for her Master degree in the US, didn't have a SSN, was using a credit card issued by a bank in her home country, her father paid the bill for her at home and didn't notice anything unusual until she finished her study and came home to look at the credit card bills.
[3] https://news.ycombinator.com/item?id=4592778