lol. Don't stress... But don't do it again!
The supervisors usually check that your student and centre number are on every page (well, they do at my school - I presume this is common practise?)
There is no reason for you to stress - you filled out the declaration saying you used 'x' no. of booklets, and ur name is on the front.
For me, once the exam is over, I go through EVERY PAGE - even if i don't write on it, it's just so they can account for every page in a booklet if some of it goes missing. But they also keep papers in school groups - procedures are in place to deal with this, i can imagine it happens a lot.
all the best mate =]