Hot Spot on Collector

I noticed the other day that the left side of my 04 360's exhaust collector has a blue-ish hot spot on it but the right side does not. The car has only 3100 miles on it. I wonder if any of you have experienced this and if there is a mixture problem. I drive the car like it was meant to be driven but it's not like I've wrung it out and abused it or anything. Maybe this is normal. What do you think could be the cause? trying to attach pictures but the images are too large. Trying to re-size and will attach later

 

Sorry, I got tied up. Here is the picture of what I'm talking about above.
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