Grey vs Black Rating Stars (in iTunes) [screenshot]

[Yero]

http://img33.imageshack.us/img33/6969/screenshot20120221at110.png

MacBook Pro (early 2011)
Mac OS X 10.7.3
iTunes 10.5.3

Hello!

Here on the screenshot, you could see grey and black rating stars in iTunes. If I click on the grey star rating to give it a new or the same rating the stars become black.

So my questions are:

1. What do they mean?
2. How are they different?
3. What could be causing it?
4. Anything else I need to know about this?

Thanks,
Yervand

 

[GGJstudios]

iTunes 10 for Mac: Rate songs and other items

 

[184550]

iTunes is guessing that's what you'll rate the material based off your previous ratings of similar material.