Hi Nemo ,
It's a good news that they touched your file even though the priority dates are not current for your case , may be it's gonna be new trend by NSC as it was recently mentioned that they are gonna do some preapproval so that once the priority dates are current those cases can be immediately approved.
So in your case there can be 2 option one which i've mentioned above second in case you have file AC21/or change yor place of residence
( different city) etc ... they might want to check your employer .
Do let us know what's your RFE is ?? and also let us know whether you changed your employer or moved to different city .
Good luck .