Flooring Tile - grout glaze

With the help of some postings here, and some leg work asking a lot of questions, I decided to tackle a kitchen counter top tile project. I used a quality porcelin tile and even beveled the face tile with my handy new $99.00 tile saw I bought at HD. It turned out great! I learned so much that I could now buy a bigger saw and set tile for a living. NOT!!
Hats off to the pros. While no longer afraid to dive in if I ever have to do it again, there's more detail in this trade than you can possibly learn doing one job.
I did however, kinda screwed up my grouting job and need to get a question answered. It's not so bad I can't live with it but it bugs me that there is some spotty grout haze I can't buff out. The grout I used is called sandstone but drys to a chocolate color. There's some chocolate and some haze down the grout line and I don't want to seal it until the color is consistant down the line.
Will the grout gradually change color on its own? or not. should I just keep buffing? any suggestions would be helpful.

There are commercial grout haze removers available. Typically, buffing very hard with a dry terry cloth towel will remove the haze.

Thanks Twelvepole,
I'll keep on buffing harder to see if I can remove the haze.

Billyjax