As long as it doesn't go above halfway, you should be fine. It is normal for the temp gauge to go up while sitting in traffic, because you are not moving at speed to get fresh air through the radiator. I don't think it should go that high though. It could very well be your thermostat, or could be your fan switch. Do your fans come on? If they do, then your car is operating normally. If not, check the thermostat and fan switch.