Using colorbar in figure produces unwanted line (seen when ungrouping in PowerPoint)

I'm making a plot that is automatically inserted into a PowerPoint presentation. This chart includes a colorbar.

The figures are more legible in powerpoint when they are ungrouped (basically turning them into a Microsoft Drawing object), but this causes a vertical line to appear above the plot outside and to the upper left.

Here is how to produce this unwanted line:

1. Run this MATLAB code (I'm running R2012b)

clf       % Clear the figure to make sure nothing is there
colorbar  % Turn on colorbar

2. Copy the figure (Edit -> Copy Figure) preserving the meta information, and paste it into PowerPoint.

3. In PowerPoint, right click on the figure, got to Group -> Ungroup, and select "Yes"

A vertical line will appear in the upper left outside, above the plot.

Does anyone know how to get rid of this line? I looked at the plot handles and couldn't figure out where it is referenced.

Thanks,

Nick