I know I am late to post on this but...
I was just at the service department a few times in the last few weeks. First to deal with some other things but while there, I asked them to check the clutch as it was having the exact same symptoms you are all describing - shudder in the shift knob, vibration etc.
I just bought the car CPO about 3 months ago with 45k and unbelievably the service manager said, let's get any last issues you see before you go out of the 50k bumper to bumper. We did a number of things that I didn't think he would do (replaced my radio because the anti-theft light didn't blink etc.) but... They said they drove it and couldn't repeat the issue with the clutch... He then followed up with "if it is doing it, just drop by and we will drive it again to see if we can repeat it". So, a few days ago, it was doing it and I stopped in. One of the techs drove it with me and WAS able to produce the shudder. So, we go back to tell the service manager and he now says "Well, the clutch is a wearable item."
Now, I JUST bought the thing CPO, put less than 3k on it and he is saying that it is WEARABLE and not covered. I asked him if there was any way I could have done it in 3k and what about the CPO check of the car and he said, "well we can't pull the transition on a CPO, we just drive it to see if it is okay..." I said, "well you didn't see it last time I was here either", to which he responded, "let me talk to BMWNA and get back to me on Monday."
From reading your posts, I am wondering if this really is a wearable issue or if it is something more. I am supposed to talk to them again on Monday so any suggestions would be appreciated!