I know it's been a while since the last message, but I've got a related problem.
Tough the fiddle doesn't work anymore, I've tried the provided code and it works well with line charts.
However, it doesn't work completely with bar charts. When you hover the mouse on the data, it display the older colour.
Here's a fiddle : http://jsfiddle.net/pAUuD/
If anyone has an idea on how to fix it.