Since i saw his Biodata on wikipedia, so i made a simple answer on why our Prime Minister likes the number 13.
I do not whether this is true or not.
Parliament Dissolved date : 13/2/2008
1. His birthday date is 26 November, 26-11-1939.
So, 26 divided by 2 is equal to 13. 26/2=13.
Then, to get the month of his birthday, November.
Just 13-2=11. Where 13 is date, 2 is month(February) and 11 is our PM's birthday's month.
2. Our PM do not want to miss his Valentine's Day with Datin Seri Jeanne Abdullah, his spouse. Maybe our PM want some relaxation too although he need to work hard on this coming Election. So, better announce it-lah. As we know, Valentine's day, man need to do something so that can make his partner happy and sweet memories. Maybe PM will make a surprise tomorrow! Roses? Chacolate? Kisses? I also do not know...
This is my opinion only, maybe it is not correct.