A wipedown with acetone or MEK (don't forget latex gloves) will get rid of the wd-40. TSP might do it. If you don't sand though, you will get those #@&*?!~ fisheyes looking at you through the next coat, unless you are exceptionally good with the resin application. It won't hurt the glass if you sand down to it but not through it. You'll see what I mean when you do it.