Thanks for the explanation, xSPRINTERx, but that means there's an amazing coincidence, because when djrod, the OP, posted a photo of his screen, I noticed a very similar colour variation on his menu bar. The colour is very similar to the colour in the photo of your menu bar and it varies left to right in the same way! Not only must djrod's menu bar must be set to translucent, but the colour provided by the picture in the background must be very nearly identical!I have my menu bar set to translucent, the colour you can see is the picture in the back ground.
I didn't realize the menu bar could be transparent; perhaps it appeared after Tiger, which we're still using.