It doesn't really matter if one experiences this or not. I did, and it prompted me to look on the internet if others experienced this too.
Pushing the lever down is harder than with previous builds I made, also the cpu didn't really wanted to slide in the socket as it used to be with other platforms, still, I made sure it fitted correctly. While pushing the lever down, the resistance from the whole mechanism creates a sound, you can hear the plastic, it's not really cracking, but it doesn't sound comfortable.
Apparently others experienced this also, and if one has not, so be it. Wouldn't be the first time.
There are three screws holding the cpu cover in place, the bottom one sits deeper than the top two. I unscrewed the bottom one a bit, and found there was no sound anymore setting the lever in place. The cpu bracket has a small sloop downwards, I checked this with a credit card, because of this sloop, a heatsink with a bigger surface than that of the cpu bracket stands a chance of resting on one side of the bracket, thus not touching the cpu completely.
Now ofcourse the stock heatsink has a round copper surface which fits perfectly in the cpu bracket since it is elevated a bit from the rest of the heatsink. Not so with many aftermarket coolers. Tightening the bottom screw all the way makes the cover from the cpu bracket fit tighter also. This is probably why the sound occurs.
I hope I made things a bit clearer, especially since english is not my native language, therefor I have to guess a bit about the proper names for all the cpu components.