03-03-2017, 07:50 AM
I've seen it many times too. Sometimes rubber backing from the mats can stain the floor underneath the mat with a yellow/brown coloring. I've seen it happen a lot with older mats in the past. You may want to replace the mats with newer mats. I think that newer better quality mats tend to leach less yellow/brown from the rubber backing to the floor than the older mats did. I say that only because we've had mats at our office for a few years, and they don't leach any color to the tile floor underneath the mat. I'd recommend new mats. If you need help sourcing good mats let me know.