Anti-alias bug caused by text color for narrow font

I am having a problem with the anti-alias that is applied to my text.

I am using a sans-serif narrow font and this problem appears based on the color that I set to the text.

From 000000 to c8c8c8, the font is displayed properly. From c9c9c9 to ffffff, the font is displayed with what I think is a lot of anti-alias, so much that it looks like it is bold.

I have tested a different font and this is not happening with other fonts.

Any ideas on what is happening and what I can try ? Can it be a font problem ? Or a Flash problem of dealing with narrow fonts ?