silestone discoloration

Hi,
We just purchased a home where silestone kitchen counters were installed in 2003. We just noticed that on either side of the stove, the front half of the silestone ( a whole band) is darker than the back half. With lights off, it's the same. The lighter color in the rear of the counter is the same color that we see throughout the kitchen.
Undoubtedly there were small appliances on the counter at the rear of the counter, but that doesn't explain why only the front of one of the several kitchen counters has darkened.
What are your suggestions? If we leave everything off the counters for several weeks, will the color start to even off?
There are no windows in the kitchen. There are windows in the family room that the kitchen opens up to.
Thank you so much.
ndesco