I ran into a error when trying to use a template to provide an axis label. After digging into it further, it appears that the chart resolves its axis labels twice when there is no font associated with the label, and the first time through the series data isn't fully populated, and the value that is passed in is not the final value.
Here is a dojo for reference. If you run this, the console will have messages where the series data element is undefined and for one set of values, followed by messages where it is defined with the correct values. If you then uncomment the font line in the valueAxis label definition and run it again, the console will only have messages where the series data element is defined.
I don't know if it's a bug, but it certainly caught me by surprise.