In case it helps you or anyone else who reads this post, the solution I got back from Shinobi regarding my original problem had to do with how I was setting the center of the tickLabel in beforeAddingToAxis. In my particular case, the following code resolved the problem:
if ([axis isXAxis])
tickMark.tickLabel.numberOfLines = 2;
CGPoint centre = tickMark.tickMarkView.center;
tickMark.tickLabel.center = centre;
I think in some older versions of Shinobi you could get away with an "off-center center" ticklabel, but the more recent versions are a little more finicky.