I have the same stiffness whether I use the one that came with the phone or any of the others I have lying round. I guess it only takes a fraction of a mm for you to get a wobble. I guess just be careful to always pull it out correctly, just to be sure.
I was actually worried about the same thing a few weeks ago as mine wiggles. But I tried different cables on different devices I have includuding a blackberry and they all have a little wiggle to them. I never lose data connection when connected to PC when flashing or charge connection...not sure if you do. If not, I wouldn't worry as I think they do tend to have some wiggle after a while.
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