Nintendo DS quality differences?

[Synful Serenity]

I've heard that quality varies depending on when and where a particular DS was manufactured, such as sturdiness of the plastic and construction....but I can't find anything substantial on that....Does this also apply to the D-pad? I ask because it seems unusually clicky, like if I am holding it down to the right and move it diagonally upwards, I feel more clicking, which feels weird because the pad is already being held down (i tend to keep my thumb towards the middle and roll it to move)....It makes me wonder if a different revision would feel smoother, and if there are other quality differences.....Maybe I am just not used to this from using other controllers and it's like this for all DSs?

 

[Doward]

I doubt there is any difference in the DS's themselves - I noticed the same thing on my DS, but no problems with it...