Ubuntu Servers :: Changed Group But Can't See The Difference

I have set up Ubuntu 10.04 and am running it on a VPS. I have everything the way I want it but I have encountered a problem. When I created my user, I did this:

adduser myname

that worked fine, it also assigned me to group called myname, which isn't what i wanted. so i tried to change my group to staff with the following:

sudo usermod -g staff myname

it works fine and i can verify my new group by:

groups myname

and get:

staff

but...now here come the bit I don't understand, when I make a new file/folder and then look at their ownership it is the old group (ie. myname). is this right? shouldn't the ownership of the file now be myname staff? not myname myname.

this is what i did to create a new file, while logged in under myname:

touch a
mkdir da
ls -al