Hi David,
Yes, it is a display glitch in the zoom level case in the video (i.e. the note will still sound at the right pitch), but it seems to be related to the bigger issue noted in my first post (notes jumping down an octave when moved slightly with the mouse etc...) - I would chalk it up to maybe a graphics card issue or a bug in the OS but this issue is only occurring in Logic and only in the Piano roll editing environment, so it seems like there is something buggy in the combo of graphics card, current OS, and the way Logic's piano roll interacts with them. Thanks for taking the time to reply, I'll post more if I find any further insight.