origin/branchname and tracking branch pointing to different commits?

Hi,

Could you, please, help me to understand how it is  possible to have a
tracking branch named qa which tracks origin/qa both pointing to
different commits after git pull origin qa?

I.e. I currently see this picture in my repository when

$ git co qa
$git log

gives me qa branch history advanced by 4 commits comparing to origin/qa

while

$git pull origin qa

says it is already up to date

So, generally, speaking qa branch is fine and is in synch with the
remote mainline, but the state of local origin/qa is not clear.

Thanks,
Eugene