I have been 3d printing for 1 year now and have never had a problem. All of a suden every flat surface i try to print is rough and grainy. Im not sure what causes this but my only thought was a change in slic3r maybe messed with the extrusion rate.
Looks like over extrusion. Could be the filament, extrusion multiplier or filament diameter not set correctly. Maybe even temp or speed.
Verify settings and try with another filament.