ICA requested my parents' CV and scheduled to
interviewed me before granting PR, it takes only few weeks for the whole procedure!
It may be due to one of your family members work for government or military
It should be quite routine check for most people.
Btw: Such questions will be directed to 疑难问答 in future. However, we will try to dig out old PR and other visa-related information in 狮城生活 and put it here as reference