I don't know about "locked into", because the Oly 60mm macro focuses amazingly on the same body at the same res and framerate (I was tracking butterflies walking along a fence at 1:1, it was incredible). And it doesn't shudder at 60p, only 24p.
That said, I have indeed started the process of trading it in (can't return it as I registered it before discovering the issue, whoops) and am effectively swapping it for the Panasonic 8-18mm and I'll re-run the same test on it once received.
I've re-run the test with the Panasonic Leica 8-18mm and it does not exhibit any focus shake in any circumstances. So, I guess this is a lesson of "pair manufacturer bodies with manufacturer lenses", at least when it comes to video.