You can remove them with slight burnishing or even, yes - a propane torch. Hit the spots with a steady movement of the torch over the area. You want to *just* heat them up, not melt plastic(!) This will gloss up with plastic and darken it again. The best would be one of those mini soldering iron type torches, but a bigger one should do in a pinch.

Or, just do what I've been doing - cover 'em up with Mother's "Back to Black."