I'm sure its not too big a deal - plenty of people would have forgotten, especially in the earlier exams. Maybe they'll send u a letter to confirm u were there or maybe you could ring up the board???
Yeah they say if you leave before the blue sheet is signed your presentation for the exam can be treated as a breach of exam rules. lol I know the words off by heart nearly.
yeah.. at my school the supervisors fully check your booklets and make sure you signed the sheet and wrote your student number + centre number b4 you can go
Don't worry. I did exactly the same thing for the AOS exam. I rang up the Board of Studies and they said it's just for administration use. I started freaking out about it thinking that they wont mark my exam. Technically, it would be the supervisor's fault. I did let the supervisors know about it and they said it would be their fault.