The first list-item in listviews has "glowing" corners on top, because the first child-div of the list-item misses the ui-corner-top class.
This is just visible, if the listview has a darker background color like with the a or b swatch and it's invisible with the c or d swatch.
At http://jsfiddle.net/MauriceG/MLBSY/ i've built a demo, where you're able to change the data-content-theme on the fly.
So you can see the glowing corners with different swatches.
More details here: For more detail please visit: http://forum.jquery.com/topic/white-line-above-listview
fix for #2528 listviews: first list-item has "glowing" corners on top
Thanks! Can you submit as a pull?
Yes! The pull is #2768 and waits for review .
Fix for issue #2528 removing listviews glowing corners
Looks great MauriceG! Fixed now.