A small imperfection in paint finish?

Question:I recently applied brasso (rub firmly for 20secs) on my piano black finish plastic which is supposingly clear coated since I polish but find no paint residue on my cloth in hope to remove fine scratches as suggested by most ppl when it can clear scratches on a ipod which is also plastic made. After the brasso application, the scratches has subside and not visible unless stared but find another discovery. I find sort of like water mark from the spot I just polished. It is very faint that I cannot see it within 5cm and 90 degree angle (good light condition) from the bottom. It does not cause any abnormality to the gloss in any way. Although it is a small problem but wish to know what causes it to have this water mark and any safe remedy to remove the water mark caused by brasso. I heard vinegar can resolve but this method is cured for "water" mark not "brasso" mark.. Pls enlighten.

Answers:
Try some car wax