I had this on my wife's S3; the issue is Google Play has not linked your Gmail account to the play store.
1st try going into settings --> application manager --> scroll right to "All" --> select Google Play Store --> Clear Data.
Reboot the phone and see if it happens again. If it does, follow the steps again except before you reboot, see if you can delete/remove your gmail account (since it is not tied to the Market, you should be able to). Then reboot the phone.
This time before you add your gmail back in, open the play store and enter your gmail info there, that should link your gmail to the play store correctly.