Before resorting to sanding, I would try a high grade (at least 91%) alcohol to try and strip the (water-based?) varathane. Since it's fresh, it may come off. You may lose some of your touch up work, but likely won't affect the original paint. The last thing you want to do is sand through that and really make things bad! I agree with others about using really light coats with Varathane, esp. after applying water slide decals. I have only done that a couple times for small stuff like the Gottlieb trademark logo, so have minimal experience with that.