Hi Denise. Did you ever get to the bottom of this? I know your post was a number of years ago but we seem to have a similar issue. We had a tiler out to take a look and he reckons its a plumbing issue; then the plumber came today and reckons its a tiling issue. Any light you can shed on it from your situation would be most helpful. Thanks.Today I suddenly noticed this grayish discoloration on my kitchen tiles near the fridge. It was not wet when I spotted it. I thought it was a shadow at first. Has anyone ever seen anything like this? Do you know what could have caused it and how to remove it?