http://www.pentaxforums.com/forums/172-pentax-k-3/254464-k3-crazy-mirror-sickness-mirror-flapping-lockup-report-yours-here.html
As we can see, there are so many K-3 users, in a total of 71 numbers, reported the same mirror sickness problem. It is concluded that the issue is simply not isolated and it is just serious and common enough.
Some K-3 users are really pissed off and they are much disappointed/upset/angered. Look at this recent example and detailed user report:
http://www.dpreview.com/forums/thread/3652110#forum-post-53460592