We have polished concrete floors in our house (including kitchen) and in a rental property we have. I have noticed the rental house has grease marks on the kitchen floor, that I'm working on removing. This has not happened in my house as I clean spills immediately and clean frequently. I'm wondering if this is normal for polished concrete floors or if they haven't been sealed properly? At the time of the build, everyone I asked said these floors were a breeze for maintenance. Now I'm a bit worried because of this grease issue. Is this normal or could something be wrong?