This is a quality problem that was discovered on the earlier years of the wetheads, yours (and mine) are included. There are quite a few discussions on the issue, in this forum, in the past. BMW had been taking care of the issue, when discovered in the past, and hopefully they will also take care of the issue now!
BTW,
muffin, there is another issue that was discovered on the earlier wetheads that you may want to keep in mind. It seems that the earlier years wetheads have another quality issue from the factory, where the cams and position sensor were out of position from where they are supposed to be! Lee (LAF) had done very extensive report on this issue, and had helped many riders to bring their cams into specifications. Three special tools are required, and they are not cheap. I had mine checked by my dealer (whom I trust completely) when my RT went in for new tires, and my cam timing was fine, while the position sensor was off, and therefore was adjusted. I would have had the work done earlier, but my RT had been running quite well, and therefore I didn't think that I had any issues. Lee had also offered to do the work for me, but in this case I wanted to support my dealer a little, since I do all of the maintenance works myself.
If you are interested in learning more about the cam timing issue, you can go through this long thread:
12K Cam Timing Lee also compiled a statistic on the number of boxers that he had checked and how many had issues. I believe that you will find the tabulation somewhere near the end of the thread. Hey Lee, if you are reading this, what is the latest model year boxer that you have seen with the timing issue?