temp can vary just by room position as well......
Near a door, a window, in sunlight, in shade, over a pipe in the floor, in airflow, close to wall, close to radiator!
Etc.
You could swop them round to see if the same is still hotter, But like James says if its running fin and sound great thats all that matters.
If it is WAY different - too hot to touch vs luke warm then I would be concerned.
Andy.