Yes, AmericaninQuebec is right. According to the Family Class Sponsorship Manual at
www .cic.gc.ca/english/resources/manuals/op/op02-eng.pdf
(sorry, I'm not allowed to post links yet, but just copy/paste it and delete the space between www and .)
Item 5.4
5.4. Lock-in age of dependent children
The lock-in of age for dependent children is the day CPC-M receives a completed IMM 1344AE
and correct processing fees. Dependent children must be less than 22 years of age when the
sponsorship application is received.
You needed to be under 22 when the form 1344AE was received by the CPC-M, that form was submitted by your brother in 2008, at the beginning of the sponsorship process, so don't worry, really.
All you need to do is be single (and even older 22) when they decide to give you the Visa and you land, and it's actually logical, why would you be dependent on your parents if you're married, right?

Good luck!