I was just at a light a few minutes ago after driving only a mile, and I noticed the temperature gauge go up to 3/4 while sitting idle for approx 15 seconds at a light. Once I started moving again, it went back down to the 1/2 mark where it should be. I have never EVER seen a car go more than a millimeter or so over the 1/2 mark. Can anyone tell me what may cause this, and if it is cause for concern. Because I'm concerned...