[Chris Noll]

Thanks Vince, as is normally the case..the minute I finally post my question, I come up with the answer.

The problem was/is that the pixel grid is not aligned with the artboard. Therefore when illustrator saves for web and devices it shifts everything and blurs it to align with the artboard and the pixel grid. This causes a semitransparent pixel along the left edge that is hardly noticeable in the .png but Illustrator sees it as a partial pixel when placing and adjusts accordingly. It can be seen by using pixel preview before exporting. Once I set my art board to the pixel grid I saw the layer that was causing the problem, moved it to a full pixel and viola! the exported .png matches pefectly.

Hope this helps the next person who has this problem.

LVC