All by itself the temp gauge rising a bit while at a stop is not alarming.
It's normal because there is no airflow through the radiator.  Once the
engine reaches a certain temperature the fan should kick in and bring the
car back to a slightly lower temperature.  This should happen if you're
standing still or moving slowly in traffic.  If you're tooling down the
highway the fan will often not come on at all.

So, how much  does your temp rise at a stop light?  If you just let the car
idle curbside, does it rise to a point and then fall again when the fan
starts?  If so, it's working as it should.  Some cars have a really sluggish
temperature gauge and you often won't notice much movement of the temp gauge
at an idle, but others show a pretty noticeable movement.  As long as it's
not going up close to the red zone you really don't have a problem.