new lcd screen, brightness unstable in the first minute...

[k0NRaD]

I recently replaced the whole lcd assembly to one of my x61s (the original one was too dim and yellowish). I bought it from a reputable seller from china (he sells original parts). He put the pieces together for me, i just replaced the whole screen once it arrived to my door.
The screen is as expected, bright, no light leakage... but I noticed a "weird" detail (and very difficult to spot i should say). When I turn the screen on or lower a lot the brightness, after some seconds (lets say from 10 to 30) the brightness of the panel becomes unstable for a litte while (let's say 10 seconds), then it stabilizes and it stays perfect until i change it again (or the screen goes off). For being unstable I mean that it changes levels of brightness very little, like a "pulse".
I know I am a little OCD with my thinkpads, im just wondering if I should consider this "normal" or not. what could be the problem? I was considering the inverter (which should be new like the screen and the lcd wire), but i guess if it were faulty it would be faulty all the time and not just in the very beginning of the brightness change. Could it be the lamp itself? what should you do in my shoes?
by the way the screen is LTN121XJ-L06 (samsung).

here a pic of the x61s, as you can see it is very bright!

http://www.flickr.com/photos/74474264@N04/6794751633/