First I would verify the thermometer is accurate. A cup of ice water will give you 32 degrees exactly.
Second the fridge side may have over chilled trying to get down to commanded temp. Open the door and allow the temp to rise a few degrees above what the temp is set for then give the fridge time to get down to set temp and check again.
Third where you are measuring the temp will have an effect. At the vent it will be very cold just like an air conditioner. Move your thermometer to the center rack.
Since it's not an absorption fridge your best source of info or repair help is you local home fridge expert. Take the coach to them and I bet just to have a look inside your coach they would give free advise.