No it doesn't, I can only notice it on a monotone color....something bright like white especially.
And you're viewing it on center and perpendicular vs above center or tilted? Also, contrast settings can change how bright the lighter colors look, esp white. A lot of TN panels now a days advertise extremely high DCR presets, but they almost always ruin color quality and can often make whites look too bright, even glowy.
If it does only show on the top half of the screen though, esp when viewing on center, it's probably a problem with the intensity and or placement of the top CCFL or panel itself, in which case they'll prefer to replace vs fix. It's best to make sure it's not caused by or made worse by a setting though, esp if it's minor, because all panels have some slight quirks and the one you exchange for could be worse.
The problem you're describing should be most noticeable when the screen is blank (all black) and you're viewing it in a dark room with no lighting. If in that scenario it's obvious, then yeah, it's most likely uneven back lighting.