puzzling cron job!!

[Vineeta <vineeta vidya aptech ac in>]

I have the foll. entry in my crontab file for root:
0 19 9 10 5 /etc/xxx          
1 19 9 10 5 /usr/bin/yyy   

This was the change i had made in the crontab file on 9th oct,1998.
After that i did not reboot my linux box.
Now,today when i came & checked my mail,i saw that the cron job was 
executed yesterday at 7pm.
Between 9th oct & today i rebooted my m/c on 28th oct,1998.
I am puzzled as to how cron works.
Acc. to the entry in crontab file the job was supposed to be executed
on 9/10/98 at 19:00 & 19:01.
then,why did it execute yesterday???
It did not execute on 9th oct.

Any idea what's going on??

Regards,
Vineeta