simplified case:
http://zkfiddle.org/sample/g4v842/4-Listheader-not-aligned-with-cells

original example:
http://zkfiddle.org/sample/nvsp9d/2-Listheader-not-aligned-with-cells

both cases combine undefined widths with hflex on the <listheader> elements
This issus is already fixed in ZK 7.0.2

a workaround is to define a width on each <listheader>
see here
http://zkfiddle.org/sample/g4v842/5-Listheader-not-aligned-with-cells
and there
http://zkfiddle.org/sample/nvsp9d/3-Listheader-not-aligned-with-cells