I am having the same problem. It appears to be a problem with JTable and the selection model it implements.
In your example the JTable sees rows 2 and 3 and columns 2 and 3 as being selected.
Assuming you have cell selection enabled on the table then JTable sees the intersection of the selected rows and columns as being selected and so cells (2,2), (2,3), (3,2) and (3,3) are displayed as selected. If you try to select cell (2,4) then you should see that the selected cells now appear as (2,2), (2,3) and (2,4) as you are effectively selecting column 4 and deselecting row 3.
I don't know the solution to this one yet, other that overriding the selection yourself but I am continuing to look into it.