Oil leak caused stains on neighbors driveway
I share a small driveway with my neighbors. I recently had my oil changed and due to a mistake from the car dealer, my oil leaked in the driveway. When I noticed it, I immediately called the dealer and they towed and fixed the problem and gave me something to put on the oil. My neighbors had a problem with this material and when it was going to rain the next day, they asked me to remove it so it did not damage their grass or get in their sump pump (which is not near the driveway). I obliged but over the next week used a degreaser. Now they are complaining that the materials I used to clean up the spill have left a mark on their driveway and they would like me to pay to have it fixed. I have to admit that everything does flow to their side and there are flow marks probably from the cleaner-but there are no actual oil stains.
My questions are, is the dealership that caused the leak responsible and am I responsible for my neighbors driveway?