Without examining your floor myself I can only guess. Most likely the grout haze was not removed after the floor was grouted. If this is the case then your installers need to come back to correct the situation. Usually, this haze can be removed with a couple of dry terry cloth towels but if won't easily come off there are products available to remove this haze.

I would recommend using TileLab grout haze remover but only as a last resort:

 www.custombuildingproducts.com/Pro...

If you end up using a haze remover yourself, use caution as it may be mildly acidic and could potentially etch your floor. Do a test spot in a hidden area first.

Let us know what happens and if you need any more adice. Good luck!

Thanks for the tips.  I'm going to give that a try.