What is a hipster? Look at this fucking hipster...

I'm watching that uni challenge now, but I don;t get why i got a question wrong:

3rd of March 2009 was a square root day as 03/03/09, when was the last square root day before it?

I thought 01/01/01, but the answer was 09/09/81. Why am I wrong?

Square Root Day occurs on the following dates each century:

[]1/1/01
[]2/2/04
[]3/3/09
[]4/4/16
[]5/5/25
[]6/6/36
[]7/7/49
[]8/8/64
[*]9/9/81

Surely the previous square root day to 3/3/09 would have had to be 2/2/04?

There's probably something terribly clever behind this.