No. When the Thatch is new and first exposed to the rain, the palm sometimes leaches a natural runoff that can spot on the ground, but that washes off. If you're installing it near fresh cement without sealer then the runoff can damage the newly placed cement. We recommend your floor have a sealer to avoid damage done by runoff. To avoid unnecessary cleanup work, the thatch should be thoroughly hosed down.  This may be repeated a couple of times. Very rarely excessive humidity in the environment can cause light mildew spotting of the palm material to occur. This can be left alone with no ill-effect to the palm or can be partially removed by spraying the affected area with 25% bleach / 75% water mixture. Then thoroughly hosing off the affected areas. Do this on a Sunny Day.