Trying to merge dev into master.

Something doesn't seem to be working right. I merged the dev branch into the master branch (using the windows git client), and everything seemed to work okay, but on Github it says the dev branch is 3 commits ahead, and 2 behind the master, which doesn't make sense to me, since they are now the same. I seem to be missing something. I thought merging would just merge all the changes into the master, and then dev would be 0 ahead, and 0 behind. But that isn't the case...