It might be a problem with the condensor fan not working, or not working properly, but if the fridge and freezer and condensor fan do seem to be working properly, then CLEAN THE DUST OFF THE CONDENSER COIL. Even a thin coating of dust on the coils can create a zone of stagnant air around the coil, greatly hindering heat transfer out of the coil. You want that condensor coil to be clean as a whistle when the wind is blowing over it to get the most efficient heat transfer out of the refrigerant.
Also, I'm thinking it's just a Yoder loop through that part of the fridge cabinet.
Years ago, they used to install electric mullion heaters under the steel mullion between the fridge and freezer sections on a standard frost free fridge. The purpose of this mullion heater was to keep the mullion warm so that condensation (and even frost) didn't form on it. On those old fridges, you'd often find an "energy saver" switch that simply turned off that mullion heater since you really didn't need it in dryer climates.
But, with all of the concern over energy efficiency in the past 20 years, they've replaced electric mullion heaters with Yoder loops. A Yoder loop is simply running the hot refrigerant that comes out of the compressor through a loop under the places you want to keep condensation (or frost) from forming on before you run that refrigerant through the condensor coil for cooling.
So, if the freezer isn't cool enough, there may be a problem. There's a real good chance that problem is just due to dust. In these forums, however, we often get people expressing surprise and concern that the mullion between the fridge and freezer is warm, or that they feel warm areas on the outside of a chest style freezer. Some heat there is normal, but if it's concerning you, check the operation of the condensor fan, and clean the condensor coil cuz dust plays a real big role in interfering with effective heat loss via convection.
Check your fridge's thermostat, too. It may have been moved inadvertantly.