It is normal for the top and sides of the unit to be warm or hot to the touch during normal operation. Make sure that you have an inch of air space around the case to allow good airflow.
Top, Front, and Sides
This is normal. Part of the cooling process is removing heat from inside the refrigerator. In the process of pulling heat from the refrigerator, some of that heat is transferred to the sides and top of the unit to reduce condensation buildup. Additionally heat is applied to the edge of the door frame and between the doors to reduce condensation buildup during humid days.
Rear and Sides
In the rear of the refrigerator, the condenser (the black radiator) on the back of the refrigerator gets hot as the inside of the fresh food or freezer section gets cold. On hot days, the condenser has to work harder to get rid of the heat created by keeping the refrigerator cold.