Hi Cinamin,
It might vary from fraternity to fraternity, but yes, it is a typical tradition for members of IFC to "lavelier" their girlfriends when things get pretty serious. Some might consider it a pre-engagement LOL-but don't get nervous now!
Often when a fraternity member laveliers his girlfriend his brothers will play a "prank" on him for "giving away" his letters. But, it is all done in good fun and tradition.
Good Luck!