I have had 3 slabs of Taj Mahal on hold for over a year and a half, 2 of them have been sitting outside for the past year; recently we went to see how our tile choices would look with the counters and noticed that there were large yellow stains toward the end of each slab. The 3rd slab that is still at the distributor does not have those stains (it has been stored inside & outside). Has anyone seen or experienced this before? The fabricator said perhaps it has something to do with the leathering process and UV from being outside. Any insight is appreciated.