I reported the issue to the cufón dev, https://github.com/sorccu/cufon/issues/239
Found the relevant issue on the modernizr project, https://github.com/Modernizr/Modernizr/issues/534
And followed it to the root issue on the html5shiv, https://github.com/aFarkas/html5shiv/issues/54
From there I went to https://github.com/aFarkas/html5shiv/commit/9aa5bcdca367fd86ec5d5b73ca4d95e032a0f502#diff-1 and figured out what exactly I would need to fix the problem.
Thinking I could ditch modernizr and just use the most up to date html5shiv at http://code.google.com/p/html5shiv/