Perhaps you might have to "git pull" the new branch in, but once its local it should just be that. Depends on how you cloned the repo in the first place, or how you got the souce.
 

Mhmmm... try doing a "git pull". Or check with a tool like "gitg" to see the status of the branches ( make sure to select "All Branches" in the drop down to see the branches in the repo, not just local ones)

Gitg screeny here: https://sites.google.com/site/harryhaaren/Home/gitg_all_branches.png

Best, -Harry