Datagrid with graphic cell background problem

I've got a datagrid and some of the entries belong to a specific "channel." Instead of putting text in the cells to indicate the channel I want to include a logo. I created a custom cell renderer, but I first have to wonder if there is an easier/better way.

In any event the graphic is showing up and it is working like I would expect, except...

For some reason the background of the cell with logo graphic in it is only half height. I have set the row height on the datagrid to 38. The cells in other columns are looking correct. Also if I trace out the height of "this" in the cell renderer class it tells me that it is 38. But clearly somewhere along the route that information isn't getting to the background.

Any ideas?