Ahh, yes, the axis titles are in italics. I don't believe there is a way to change that in the API. If you are willing to mess with the SVG/VML of the charts, then you can do this. Here's a script that changes all italic text in the chart to non-italics:
http://jsfiddle.net/asgallant/AcuHp/. Note that the script uses jQuery for browser detection and document manipulation; you can do all of this with other libraries or plain js if you don't use jQuery. Also note that since this is messing with the internal code, it could break at any time with an update to the API; none of the internal structure of the charts is guaranteed to be stable across releases. That said, you're probably safe with this one, as it doesn't muck about with anything critical to the charts.