My cement patio was replaced about 6 months ago. My patio doesn't get much sun on it during the day and I have noticed now that the leaves are coming down they are staining the patio after it rains. I try to get the wet leaves off as soon as I can but not always possible. The patio is now stained in a black color with blotches all over . I have called the contractor back who poured the patio, but I just wanted to get some background as to why this might be happening, Since I have no experience with cement I wouldn't know the truth from an excuse. It seems the only way of cleaning up the blotches is power washing the patio, which is not an option since I live in a Condo and I'm sure the water has been turned off by now. (I live on Long Island, NY) Should this patio have been sealed after it cured? The contractor said nothing about sealing it after the job was completed. Thanks in advance for any insight about the stains.